Refrigerator

ABSTRACT

The refrigerator includes a cabinet having a storage compartment therein, an illumination device for illuminating the interior of the storage compartment, a door hinged to the cabinet for opening and closing the storage compartment, the door having an opening formed therein and a panel assembly having a front panel provided at the front thereof, a knock sensor module including a microphone module for sensing a sound wave generated by knock vibration applied to the door and a module microcomputer for determining whether the knock vibration is a predetermined knock based on the sensed sound wave, and a controller provided separately from the module microcomputer for receiving a knock-on signal from the module microcomputer and operating the illumination device such that light is transmitted through the panel assembly, whereby the interior of the storage compartment can be seen from outside the door.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation Application of prior U.S. patentapplication Ser. No. 16/448,448, filed on Jun. 21, 2019, which is aContinuation of Ser. No. 15/310,043 filed Nov. 9, 2016, which is a U.S.National Phase Application under 35 U.S.C. § 371 of InternationalApplication PCT/KR2016/009413 filed on Aug. 25, 2016, which claims thebenefit of Korean Application No. 10-2015-0119526 filed on Aug. 25,2015, whose entire disclosure is/are hereby incorporated by reference.

BACKGROUND 1. Field

The present invention relates to a refrigerator, and more particularly,to a refrigerator including a door that is variably transparent so thatthe interior of the refrigerator is visible therethrough.

2. Background

In general, a refrigerator is an apparatus that discharges cool airgenerated by a refrigerating cycle involving a compressor, a condenser,an expansion valve, and an evaporator to lower the temperature in therefrigerator such that food is stored in a frozen state or in arefrigerated state.

A refrigerator generally includes a freezing compartment for storingfood or beverages in a frozen state and a refrigerating compartment forstoring food or beverages in a refrigerated state.

Refrigerators are classified into a top mount type refrigerator, inwhich a freezing compartment is disposed above a refrigeratingcompartment, a bottom freezer type refrigerator, in which a freezingcompartment is disposed under a refrigerating compartment, or a side byside type refrigerator, in which a freezing compartment and arefrigerating compartment are disposed side by side. In all cases, doorsare provided at the freezing compartment and the refrigeratingcompartment such that access to the freezing compartment and therefrigerating compartment is possible through the doors.

In addition to refrigerators in which a freezing compartment and arefrigerating compartment are partitioned from each other, there arealso refrigerators in which access to a freezing compartment and arefrigerating compartment is possible through a single door. Most suchsingle door type refrigerators are small-sized, and the freezingcompartment is generally provided in a specific space inside therefrigerating compartment.

In addition, there is a French type refrigerator, in which an upperrefrigerating compartment is opened and closed by left and right doors,as a kind of top mount type refrigerator. A freezing compartment of theFrench type refrigerator may also be opened and closed by left and rightdoors.

In recent years, the functions of the refrigerator have been diversifiedin addition to the original functions of the refrigerator, includingstorage of food in a frozen state or in a refrigerated state. Forexample, a dispenser may be mounted in the door of the refrigerator toprovide clean water and ice, or a display unit may be mounted to thefront of the door to display the state of the refrigerator such that therefrigerator can be appropriately controlled.

In general, the door of the refrigerator, which is provided to open andclose the storage compartment, is opaque. That is, the door is providedas a heat insulation wall that defines the refrigerating compartment andthe freezing compartment. However, the door is a heat insulation wallthat can be opened and closed so that a user can access therefrigerating compartment or the freezing compartment. For this reason,it is not possible for the user to check the kinds and positions ofgoods stored in the storage compartment before the user opens the door.

The largest amount of cool air is lost when the door is opened. As theamount of time for which the door is open is increased, energy loss isfurther increased.

In general, various kinds of goods are stored in the refrigeratingcompartment or the freezing compartment. Consequently, it takes apredetermined amount of time for the user to find a desired item andtake it out. That is, the user looks around the storage compartment tofind a desired item in the state in which the door is open, which takesa considerable amount of time.

Such unique characteristics of the refrigerator cause user inconvenienceand increase energy consumption.

In recent years, a refrigerator configured such that a portion of thestorage compartment is openable has been proposed. That is, arefrigerator having a sub door for opening and closing a sub storagecompartment provided in a main door has been proposed. The sub storagecompartment is a portion of a main storage compartment. At least aportion of the sub storage compartment may be partitioned from the mainstorage compartment by a partition wall. The sub storage compartment maybe provided in front of the main storage compartment. This type ofrefrigerator may be called a door in door (DID) refrigerator. When thesub door is opened, the leakage of cool air from the main storagecompartment is somewhat reduced, thereby achieving an energy savingeffect.

In the DID refrigerator, the user may open the main door to access themain storage compartment. The reason for this is that when the main dooris rotated open, the sub storage compartment is also rotated togetherwith the sub door.

For example, goods that are frequently used, such as beverages, may bestored in the sub storage compartment. The sub door may be opened,without opening the main door, in order to access the sub storagecompartment.

Meanwhile, there is also a home-bar refrigerator having a home-bar door.A home bar may be a very small sub storage compartment. That is, thehome-bar door, which is mounted in a portion of the main door, may beopened to store a small number of beverages in the home bar, which isprovided in the rear of the main door.

A refrigerator having an enlarged home-bar may be considered a DIDrefrigerator.

In the DID refrigerator and the home-bar refrigerator, however, problemsmay be caused as the volume of the sub storage compartment is increasedand the number of goods stored in the sub storage compartment isincreased. That is, it takes a predetermined amount of time for the userto open the sub door or the home-bar door and to find a desired item andtake it out, which causes user inconvenience and increases energyconsumption.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments will be described in detail with reference to the followingdrawings in which like reference numerals refer to like elements and,wherein:

FIG. 1 is a perspective view showing a refrigerator according to a firstembodiment of the present invention;

FIG. 2 is a perspective view showing a right refrigerating compartmentdoor of FIG. 1;

FIG. 3 is a perspective view taken along line IV-IV of FIG. 2;

FIG. 4 is a perspective view showing a sub door of FIG. 2;

FIG. 5 is a perspective view showing a refrigerator according to asecond embodiment of the present invention;

FIG. 6 is a perspective view showing a right refrigerating compartmentdoor of FIG. 5;

FIG. 7 is a perspective view taken along line VIII-VIII of FIG. 6;

FIG. 8 is a perspective view showing a sub door of FIG. 6;

FIG. 9 is a sectional view showing the assembly of a front panel and aheat insulation panel in the manufacture of the sub door of the firstembodiment;

FIG. 10 is a block diagram showing a control configuration according toan embodiment of the present invention;

FIG. 11 is a sectional view showing a microphone module applicable to anembodiment of the present invention;

FIG. 12 is a partially cutaway perspective view showing a structure inwhich a vibration sensor (a microphone module) is mounted to the subdoor of the first embodiment;

FIG. 13 is a partial perspective view showing a structure in which avibration sensor (a microphone module) is mounted to the sub door of thesecond embodiment;

FIG. 14 is a perspective view showing the structure shown in FIG. 13;

FIG. 15 is a partially enlarged view showing a cap decoration parthaving a through hole in another embodiment of the structure in whichthe vibration sensor (the microphone module) is mounted to the sub doorof the second embodiment;

FIG. 16 is a perspective view showing the state in which a microphonemodule is mounted in the through hole shown in FIG. 15;

FIG. 17 is a perspective view showing a cover coupled to the capdecoration part shown in FIG. 15;

FIG. 18 is a conceptual view showing the position of a sub door at whicha vibration sensor (a microphone module) is mounted and the position ofthe sub door on which a user taps;

FIG. 19 is a block diagram showing a control configuration according toanother embodiment of the present invention;

FIG. 20 is a block diagram showing a control configuration according toanother embodiment of the present invention; and

FIG. 21 is a block diagram showing a control configuration according toa further embodiment of the present invention.

DETAILED DESCRIPTION

Hereinafter, preferred embodiments of the present invention will bedescribed in detail with reference to the accompanying drawings.

Embodiments of the present invention are not limited to the types ofrefrigerators previously described. That is, a main door for opening andclosing a refrigerating compartment or a freezing compartment may be asee-through door, or a sub door for opening and dosing a sub storagecompartment or a home-bar door may be a see-through door. Such ahome-bar door may also be referred to as a sub door, since the home-bardoor is hinged to the main door.

FIGS. 1 to 4 are views showing a refrigerator according to a firstembodiment of the present invention.

The refrigerator shown is a bottom freezer type refrigerator in which arefrigerating compartment is provided in the upper part of a cabinet 10and a freezing compartment is provided in the lower part of the cabinet.The refrigerating compartment and the freezing compartment may beportions of a storage compartment or a main storage compartment 11provided in the cabinet 10.

As previously described, the present invention is not limited to thistype of refrigerator. Any refrigerator having a door hinged to a cabinetfor opening and closing a storage compartment of the refrigerator may beapplied to the present invention.

In the embodiment shown, a left refrigerating compartment door 20 and aright refrigerating compartment door 25 are respectively hinged to theleft and right sides of the cabinet 10. Alternatively, a singlerefrigerating compartment door may be hinged to the cabinet.

The left refrigerating compartment door 20 is an opaque door, at thelower end of which may be provided a handle. On the other hand, theright refrigerating compartment door 25 is configured to be selectivelytransparent such that the interior of the refrigerator compartment canbe viewed through the right refrigerating compartment door 25. That is,the right refrigerating compartment door 25 may be a see-through door.

A left freezing compartment door 30 and a right freezing compartmentdoor 40 may be respectively hinged to the left and right sides of thelower part of the cabinet 10 such that the left freezing compartmentdoor and the right freezing compartment door are respectively providedunder the left refrigerating compartment door and the rightrefrigerating compartment door. Alternatively, a single freezingcompartment door may be hinged to the cabinet, or may be a drawer typedoor, which is separably mounted in the cabinet in the forward-rearwarddirection.

A handle groove 32 may be provided at the top surface of the leftfreezing compartment door 30, and a handle groove may also be providedat the top surface of the right freezing compartment door 40.

In the embodiment shown in FIG. 1, one of the doors is a see-throughdoor. Alternatively, the doors of the refrigerator may be configured assee-through doors irrespective of whether to open and close therefrigerating compartment or the freezing compartment and whether toopen and close the main storage compartment or the sub storagecompartment.

As shown in FIG. 1, the right refrigerating compartment door 25 mayinclude a main door 100 mounted to one side of the cabinet 10 so as tobe turned about a main door hinge 110 and a sub door 200 mounted to themain door 100 or the cabinet 10 so as to be turned about a sub doorhinge 130. That is, both the main door 100 and the sub door 200 may beopened to access the refrigerating compartment.

An opening may be provided in the inner middle part of the main door100, and a sub storage compartment (not shown) may be provided at therear of the main door 100.

The sub door 200 may be opened to access the sub storage compartmentthrough the opening in the main door 100. That is, only the sub door 200may be opened to access the sub storage compartment without opening themain door 100.

The sub storage compartment may be defined by mounting a plurality ofbaskets in the upward-downward direction. Specifically, a cover (notshown) for covering the baskets (not shown) may be provided. The covermay function as a partition wall for partitioning the sub storagecompartment and the main storage compartment from each other.Consequently, the sub storage compartment may be located in front of themain storage compartment.

As shown in FIG. 2, mounting protrusions 120 for mounting the basketsmay be provided on the inner surface of the rear of the opening 115 ofthe main door 100. Two or three pairs of baskets may be mounted so as tobe spaced apart from each other by a predetermined distance in theupward-downward direction. As shown in FIG. 2, therefore, the sub door200 may be opened in the state in which the main door 100 is closed suchthat a user can access the sub storage compartment 111.

The relationship between the main door and the sub door and therelationship between the main storage compartment and the sub storagecompartment are typical for a DID refrigerator, and thus a detaileddescription thereof will be omitted.

The sub door 200 is provided at the inside thereof with a panel assembly270, which may be selectively transparent. As will be described later,the panel assembly may include a plurality of panels, although the panelassembly may be constituted by a single panel. The panel assembly 270may be selectively seen through. The user may see the space inside thedoor through the panel assembly 270.

In the case in which the main door 100 and the sub door 200 areintegrally formed to constitute a single door, unlike what is shown, themain storage compartment may be seen through the panel assembly 270. Inthis case, the main door 100 may be the cabinet itself, and the sub door200 may be a door for opening and closing the storage compartment.

The sub door 200 may be provided at the left side of the panel assemblywith a groove-shaped handle 240. The handle 240 may extend in theupward-downward direction, and may have a length equal to the height ofthe panel. Of course, the sub door 200 may be a left sub door providedat the left side of the cabinet 10. In this case, the handle 240 may beformed on the opposite side.

In addition, the rotational direction of the sub door 200 may beidentical to that of the main door 100. That is, as shown in FIG. 2, themain door 100 and the sub door 200 may be provided so as to be rotatedabout a vertical rotary shaft. Alternatively, the sub door 200 may beprovided so as to be rotated about a horizontal rotary shaft, as in thehome-bar door.

In general, a door switch (see FIG. 12) for sensing opening and closingof the door is provided at the front of the cabinet of the refrigerator,and an illumination device (see FIG. 12) for illuminating the interiorof the storage compartment when the door is opened is provided in thestorage compartment.

In refrigerators according to embodiments of the present invention, thedoor may be changed to a see-through door when the illumination deviceis operated. That is, the door may be changed to a see-through door suchthat the interior of the door can be seen when the illumination deviceprovided in the main storage compartment and/or the sub storagecompartment is operated.

That is, the interior of the door cannot be seen when the illuminationdevice is not operated, and the interior of the door can be seen whenthe illumination device is operated. In particular, the panel assemblymay appear to be a black panel when the illumination device is notoperated. The change to the see-through door may be performed by userinput.

A control method and configuration related to the change to thesee-through door will be described later.

The structure of the sub door 200 will be described in detail withreference to FIGS. 3 and 4. As previously described, the sub door 200may be the main door itself for opening and closing the storagecompartment. In the case in which the sub door is hinged to the maindoor, as shown in FIG. 1, the sub door 200 may be provided so as tooverlap the main door 100. That is, the front of the sub door 200 mayoverlap the front of the main door 100. At this time, the front of thesub door 200 may constitute the front of the main door 100 and may thusconstitute the front of the refrigerator.

The sub door 200 includes a door frame 205, which has an opening formedin the inner middle part thereof. The door frame 205 defines the edge ofthe sub door 200. That is, the door frame defines the upper, lower,left, and right sides of the edge of the sub door 200.

Specifically, the door frame 205 may include an external door part 210that defines the front edge of the door and a door liner 280 thatdefines the rear edge of the door, the door liner having an openingformed in the inner middle part thereof. The external door part 210 andthe door liner 280 may have openings that correspond to the opening 211.

In addition, the door frame 205 may include cap decoration parts 260coupled to the upper and lower ends of the external door part 210 andthe door liner 280. The external door part 210, the door liner 280, andthe cap decoration parts 260 may constitute a door frame 205 having aspace defined therein while having a thickness in the forward-rearwarddirection.

In conventional refrigerators, foam for insulation is injected into aspace defined by the external door part 210, the door liner 280, and thecap decoration parts 260. In this embodiment, however, the door frame205 may include a panel assembly 270. That is, the panel assembly 270may be included in the door frame 205 in order to selectively form asee-through door. As will be described later, the panel assembly 270 mayhave a heat insulation function.

The panel assembly 270 may be provided at the middle part of the subdoor 200. In particular, the panel assembly 270 may be provided so as tocorrespond to the opening in the door frame 205.

In order to mount the panel assembly 270, the door frame 205 may furtherinclude an inner frame 230 provided between the external door part 210and the door liner 280. The inner frame 230 may be provided in themiddle part thereof with an opening, which corresponds to the opening211 in the door frame 205.

The door frame 205 may further include a door decoration part 220. Thedoor decoration part 220 may be mounted in the opening in the door frame205 so as to substantially define the opening 211 in the door frame 205.

The sub door 200 may include an upper hinge bracket 254 and a lowerhinge bracket 256 for rotatable mounting, in addition to the panelassembly 270. The sub door 200 may include a handle 240 for allowing theuser to open and close the sub door 200 while holding the handle and agasket 290 for sealing. In addition, the sub door 200 may furtherinclude supports 250.

Hereinafter, a method of assembling the sub door 200 will be describedwith reference to FIG. 4.

First, the door decoration part 220 is assembled to the external doorpart 210, and then the handle 240 is assembled. A handle support 245 maybe interposed between the handle 240 and the external door part 210 orthe door decoration part. The handle support may be made of a metal, andmay be formed in a bar shape so as to increase the rigidity of thehandle 240. The door decoration part 220 may be coupled to the rear ofthe external door part 210. In this embodiment, the handle 240 may becoupled to the left end of the external door part 210, as shown in FIG.4.

Subsequently, the inner frame 230 is assembled to the rear of theexternal door part 210, and the supports 250 and the hinge brackets 254and 356 are assembled.

The supports 250 may include an upper support and a lower support. Thesupports 250 may be formed so as to correspond to the four upper, lower,left, and right corners of the opening 211. The supports 250 areprovided so as to correspond to four corners of the panel assembly 270in order to protect the panel assembly. That is, the supports supportthe panel assembly such that the weight of the panel assembly isuniformly distributed to the door frame 205.

In addition, the hinge brackets 254 and 256 are coupled to the supports250. Consequently, the supports 250 may also function to increase therigidity of the hinge brackets.

Subsequently, the cap decoration parts 260 are coupled to the rear ofthe external door part 210. The cap decoration parts 260 may be insertedinto the upper and lower parts of the external door part 210 so as to becoupled to the external door part 210.

Subsequently, the panel assembly 270 may be coupled to the external doorpart 210 at the rear of the external door part 210, and the door liner280 may be coupled to the rear of the external door part 210. The doorliner 280 may be fixed to the external door part 210 using screws.

Finally, the gasket 290 is mounted to the rear of the door liner 280,whereby the assembly of the sub door 200 is completed.

The sub door hinge 130 may be coupled to the upper hinge bracket 254 andthe lower hinge bracket 256. When the sub door 200 is coupled to themain door 100, the gasket 290 seals the gap therebetween to prevent theleakage of cool air.

As shown in FIG. 3, the panel assembly 270 may include a front panel 271exposed to the front of the sub door 200. The front panel 271 may bemade of a transparent material. A metal may be deposited on the rear ofthe front panel 271. The metal deposition layer makes the front panel271 opaque in the state in which light is not transmitted through themetal deposition layer. On the other hand, the metal deposition layermakes the front panel 271 transparent when light is transmitted throughthe metal deposition layer.

Of course, the front panel 271 may have a color coating layer or may beformed as a colored panel. That is, the front panel may be opaque in thestate in which light is weak, and may become transparent in the case inwhich light is strong.

This means that the front panel 271 is opaque when the illuminationdevice at the rear of the front panel 271 is not operated and that thefront panel 271 becomes a transparent panel when the illumination deviceis operated. Consequently, the interior of the storage compartmentcannot be seen when the interior of the storage compartment is dark, andthe interior of the storage compartment can be seen through the frontpanel 271 when the interior of the storage compartment is bright.

The panel assembly 270 may include a heat insulation panel provided atthe rear of the front panel 271. A plurality of heat insulation panelsmay be provided. FIG. 3 shows an example in which two heat insulationpanels are provided. Intermediate bars 272 may be provided between theheat insulation panels 273 and 276 and between the front panel 271 andthe heat insulation panel 273.

The front panel 271 is made of a transparent material. The front panelis mounted in the opening formed in the middle part of the sub door 200to constitute the front of the sub door 200.

The space in the door frame 205 of the sub door, excluding the panelassembly 270, may be filled with a heat insulation material.Specifically, a heat insulation material may be injected into a spacebetween the external door part 210 and the door liner 280, i.e. a space285 formed at the edge of the sub door, in order to prevent the leakageof cool air through the gap between the gasket 290 and the panelassembly 270.

Consequently, the edge of the sub door 200 is thermally insulated by theheat insulation material, e.g. polyurethane, and the middle part of thesub door 200 is thermally insulated by the heat insulation panels 273and 276.

After the assembly of the sub door 200, foam is injected into the space285 so as to securely couple the external door part 210 and the doorliner 280 to each other.

The structure and manufacturing method of the panel assembly 270 will bedescribed in detail hereinafter.

FIGS. 5 to 8 are views showing a refrigerator according to a secondembodiment of the present invention.

In the refrigerator according to the second embodiment, as shown inFIGS. 5 and 6, a right refrigerating compartment door 25 includes a maindoor 300 hinged to the cabinet 10, the main door 300 being provided inthe inner middle part thereof with an opening, and a sub door 400 hingedto the main door 300, the sub door 300 being inserted into the openingin the main door 300.

In the refrigerator according to the first embodiment, the sizes of themain door and the sub door are the same when viewed from the front, andthe sub door may overlap the main door when the sub door is closed.

In the refrigerator according to the second embodiment, on the otherhand, the size of the sub door 400 is smaller than that of the main door300, and the sub door 400 is inserted into the opening 310 in the maindoor when the sub door is closed.

Specifically, in the previous embodiment, the sub door 200 is exposed tothe outer front side of the main door 100 in the state in which the subdoor is coupled to the main door, and, in this embodiment, the sub door200 is inserted into the main door 100 in the state in which the subdoor is coupled to the main door. The former may be referred to as anoutside type sub door, and the latter may be referred to as an insidetype sub door.

In this embodiment, the main door 300 may be the cabinet itself. In thiscase, the sub door 300 may be a door for opening and closing the storagecompartment 11.

An opening 315 may be provided in the inner middle part of the main door300, and a sub storage compartment 311 may be provided in the rear ofthe main door 300.

The sub door 400 may be opened to access the sub storage compartment 311through the opening 315 in the main door 300. That is, the sub door 400may be opened alone to access the sub storage compartment 311 withoutopening the main door 300.

The sub storage compartment may be defined by mounting a plurality ofbaskets in the upward-downward direction. Specifically, a cover (notshown) for covering the baskets (not shown) may be provided. The covermay function as a partition wall for partitioning the sub storagecompartment and the main storage compartment from each other.Consequently, the sub storage compartment may be located in front of themain storage compartment.

As shown in FIG. 6, mounting protrusions 320 for mounting the basketsmay be provided at the inner surface of the rear of the opening 315 inthe main door 300. Two or three pairs of baskets may be mounted so as tobe spaced apart from each other by a predetermined distance in theupward-downward direction. As shown in FIG. 6, therefore, the sub door400 may be opened in the state in which the main door 300 is closed suchthat a user can access the sub storage compartment 311.

Meanwhile, in this embodiment, the main door 300 may be provided withtwo openings, which include an opening 315 for access to the sub storagecompartment 311 and an opening 310 into which the sub door 400 isinserted. The opening 310 may be formed outside the opening 315.

The relationship between the main door and the sub door and therelationship between the main storage compartment and the sub storagecompartment are typical for a DID refrigerator, and thus a detaileddescription thereof will be omitted.

The sub door 400 is provided at the inside thereof with a panel assembly470, which may be selectively transparent. As will be described later,the panel assembly may include a plurality of panels, although the panelassembly may be constituted by a single panel. The panel assembly 470may be selectively transparent. The user may see the space inside thedoor through the panel assembly 470.

That is, the sub storage compartment 311 may be seen through the panelassembly, which is provided in the opening 411 in the sub door 400, andthrough the opening 315, formed in the main door 300. The interior ofthe sub storage compartment 311 may be seen in the state in which thesub door 400 is closed such that the use can easily check the kinds andpositions of goods stored in the sub storage compartment. Subsequently,the user may open the sub door 400, and may easily take desired goodsout of the sub storage compartment.

Hereinafter, the structure of the sub door 400 will be described indetail with reference to FIGS. 7 and 8.

The sub door 400 includes a door frame 405, which has an opening 411formed in the middle part thereof.

The door frame 405 may include an inner frame 410 that defines the edgeof the sub door 400 at the rear of the sub door 400 and a door liner 480that defines the rear edge of the sub door, the door liner 480 beingcoupled to the inner frame 410.

Unlike the first embodiment, the cap decoration parts may not be coupledto the upper and lower ends of the inner frame 410 and the door liner480, but may be integrally formed with the upper and lower ends of theinner frame 410 and the door liner 480.

In addition, supports 450 may be coupled to the upper and lower parts ofthe inner frame 410 and the door liner 480 therebetween.

An upper hinge bracket 454 may be coupled to one side of the uppersupport 450, and a lower hinge bracket 456 may be coupled to one side ofthe lower support 450. Sub door hinges may be coupled to the upper hingebracket 454 and the lower hinge bracket 456.

Of course, unlike what is shown, the cap decoration parts may be coupledto the upper and lower ends of the inner frame 410 and the door liner480, and an upper hinge (not shown) and a lower hinge (not shown) may bedirectly mounted to the cap decoration parts.

The door liner 480 may be provided in the rear thereof with a recess,into which a gasket 490 is inserted and mounted. When the sub door 400is coupled to the main door 300, the gasket 490 seals the gaptherebetween to prevent the leakage of cool air.

In the sub door 400 of the second embodiment, as shown in FIGS. 7 and 8,the panel assembly 470 is coupled to the front of the sub door 400. Thatis, the panel assembly 470 may be coupled to the inner frame 410 at thefront of the inner frame 410.

The panel assembly 470 may be identical or similar to the panel assembly270 of the previous embodiment. In this embodiment, however, the edge ofa front panel 471 of the panel assembly 470 is not covered by theexternal door part 210, but is coupled to the front of the inner frame410, which has an opening therein, unlike the first embodiment.

That is, in the previous embodiment, the edge of the front of the subdoor is defined by the external door part 210, and the middle part ofthe front of the sub door is defined by the front panel 271. In thisembodiment, however, the entirety of the front of the sub door may bedefined by the front panel 471. That is, the edge and the middle part ofthe front of the sub door are defined by the front panel 271.

To this end, the front panel 471 may be formed so as to be larger than aplurality of heat insulation panels 473 and 476. That is, the frontpanel 471 may extend further outward so as to cover the heat insulationpanels.

The heat insulation panels 473 and 476 may be inserted into the openingin the inner frame 410, i.e. the inner surface of the opening 411 of thesub door, and the rear surface of the second heat insulation panel 476may be supported by the door liner 480.

An intermediate bar 472 having a rectangular section may be providedbetween the front panel 471 and the first heat insulation panel 473 inorder to maintain a predetermined gap therebetween.

Meanwhile, a handle 440 may be coupled to the left side of the innerframe 410 and the door liner 480, which are coupled to each other.

In order to couple the handle 440 to the inner frame 410, the innerframe 410 may be provided at the left side thereof with a pair ofcatching ribs 412, which are engaged with a pair of coupling ribs 442formed at the left side of the handle 440 so as to extend in theupward-downward direction.

The catching ribs 412 may protrude laterally from the left side of theinner frame 410, and may then be bent forward and rearward.

Correspondingly, the coupling ribs 442 may protrude laterally from theright side of the handle 440, and may then be bent rearward and forward.

As the result of the coupling between the inner frame 410 and the doorliner 480, a predetermined space 480 is formed at the edge of the subdoor 400. The space 480 may be formed as the result of the capdecoration parts being coupled to the inner frame 410 and the door liner480. That is, the space 480 is formed at the upper, lower, left, andright sides of the edge of the sub door 400. The space is filled with aheat insulation material through a foaming process.

Consequently, the edge of the sub door 400 is thermally insulated by theheat insulation material, and the middle part of the sub door 400 isthermally insulated by the panel assembly 470.

The portion of the front panel 471 that is located outside the heatinsulation panels in the radial direction thereof may be in tightcontact with the inner frame 410. Of course, the front panel may also bein tight contact with the cap decoration parts, in addition to the innerframe 410. In the latter case, the upper and lower parts of the innerframe are formed by additional cap decoration parts.

First, after the handle 440 is coupled to the inner frame, the capdecoration parts may be coupled to the inner frame as needed.Subsequently, the panel assembly may be in tight contact with the frontof the inner frame 410. The inner frame 410 and the panel assembly maybe temporarily assembled using a piece of transparent tape or atransparent adhesive. That is, a piece of transparent tape may beattached to the rear surface of the edge of the inner frame 410 or thefront panel 471 (i.e. the portion of the inner frame or the front panelthat is located outside the heat insulation panels in the radialdirection thereof).

After the panel assembly is temporarily assembled to the inner frame410, the inner frame 410 and the door liner 480 may be coupled to eachother at the rear of the inner frame 410. Subsequently, the space 485 isfilled with foam such that the panel assembly is tightly fixed to thedoor frame 405.

Hereinafter, the structure and manufacturing method of the panelassembly will be described with reference to FIG. 9.

FIG. 9 is a conceptual view showing the panel assembly 270 of the firstembodiment, which may be identical to the panel assembly 470 of thesecond embodiment except that the size of the front panel 271 is equalto that of the heat insulation panels 273 and 276.

The front panel 271 may be thermally strengthened glass, which is formedby heating glass at a temperature of about 600 to 700

in order to increase the strength of the glass.

In the heat strengthening process, glass is heated to a glass transitiontemperature (Tg) or higher and is then rapidly cooled such that theglass has compressive stress formed due to the difference in shrinkagebetween the inside and the outside of the glass.

In the heat strengthening process, the depth of the compressive stressis about 20% the thickness of the glass.

A metal, such as titanium or nickel, may be deposited on the rearsurface of the front panel 271 to form a deposition layer 2712. When theinterior of the storage compartment is illuminated, the deposition layer2712 allows light to be transmitted through the front panel 271 suchthat the interior of the storage compartment can be seen. When theinterior of the storage compartment is not illuminated, the depositionlayer 2712 prevents the interior of the storage compartment from beingseen through the front panel 271. Of course, the front panel 271 may bemade of colored glass, or may have a colored coating layer.

Consequently, the front panel 271 may become a see-through panel whenlight is transmitted through the front panel 271, and may become a blackpanel when light is not transmitted through the front panel 271. Inaddition, even when light is transmitted through the front panel 271,the transmitted light may become dim light, unlike transmission throughnormal glass. As a result, the atmosphere of the space in which therefrigerator is installed may be improved.

The first heat insulation panel 273 and the second heat insulation panel276 may be chemically strengthened glass, which is formed by soakingglass in an electrolytic solution at a glass transition temperature orhigher to chemically strengthen the glass.

In the chemical strengthening process, glass is heated to a glasstransition temperature (Tg) or lower in an electrolytic solution havingsalt, such as KNO3, dissolved therein. As a result, some sodium ions onthe surface of the glass are replaced with potassium ions, andcompressive stress is formed in the glass due to the difference inradius between ions.

In the chemical strengthening process, the depth of the compressivestress may be about 2 to 3% the thickness of the glass.

A low-emissivity coating layer 2732 for reducing the transfer of heatinto the storage compartment due to radiation may be provided at therear surface of the first heat insulation panel 273.

Glass having a low-emissivity coating layer 2732 is called low-s glass.In general, silver is deposited on the surface of glass by sputtering toform a low-emissivity coating layer.

A vacuum space may be formed between the first heat insulation panel 273and the second heat insulation panel 276. To this end, a hole 2735 forvacuum pumping may be formed through the first heat insulation panel273.

A plug 2736 is inserted into the hole 2735 in order to close the hole2735 after vacuum pumping.

A process of coupling the first heat insulation panel 273 and the secondheat insulation panel 276 to each other and forming a vacuum heatinsulation space therebetween will be described.

First, frit glass 275 is dispensed and arranged along the edge of thesecond heat insulation panel 276. The frit glass 275 is a glass materialincluding glass powder having a melting point of about 400 to 500

and a binder. The frit glass has a melting point lower than that of theheat insulation panels 273 and 276.

After the frit glass 275 is arranged along the edge of the front of thesecond heat insulation panel 276, the first heat insulation panel 273 isplaced on the second heat insulation panel 276, and heat is applied soas to melt the frit glass 275. After the frit glass 275 is solidified,the two heat insulation panels may be coupled to each other.

Meanwhile, a plurality of spacers 274 is arranged after the frit glass275 is arranged and before the first heat insulation panel 273 is placedon the second heat insulation panel 276.

The spacers 274 prevent the middle parts of the heat insulation panelsfrom curving, since there is a limitation on extent to which thethickness and strength of the heat insulation panels, which are made ofglass, can be increased.

The spacers 274 may be made of stainless steel, glass, or plastic. Thespacers 274 may be made of a material that is capable of preventing heattransfer due to conduction while maintaining the gap between the firstheat insulation panel 273 and the second heat insulation panel 276.

After the first heat insulation panel 273 and the second heat insulationpanel 276 are coupled to each other, vacuum pumping is performed throughthe hole 2735 to form a vacuum space therein.

After vacuum pumping, the plug 2736 is inserted into the hole 2735. Fritglass 2737 may be further melted on the first heat insulation panel soas to cover the plug. In this case, the plug 2736 may not protrude fromthe surface of the first heat insulation panel 273, and the melted fritglass may slightly convexly protrude from the surface of the first heatinsulation panel.

The frit glass 2737 may have a melting point that is lower than that ofthe frit glass 275, which is disposed between the two heat insulationpanels.

After the coupling of the first heat insulation panel 273 and the secondheat insulation panel 276, vacuum pumping, and sealing are allcompleted, quadrangular intermediate bars 272 having a predeterminedthickness are disposed on the front surface of the first heat insulationpanel 273, and the front panel 271 is attached to the intermediate bars.

A transparent adhesive may be applied between the intermediate bars 272and the first heat insulation panel 273 and between the intermediatebars 272 and the second heat insulation panel 276 in order to bond theintermediate bars to the first heat insulation panel and to bond theintermediate bars to the second heat insulation panel.

The panel assembly 270, manufactured as described above, is disposedbetween the external door part 210 and the door liner 280, and theexternal door part 210 and the door liner 280 are coupled to each other,as shown in FIG. 4, whereby the sub door 200 is completed.

In the second embodiment, the panel assembly 470 may be attached to thefront of the inner frame 410 using a transparent adhesive. At this time,the first heat insulation panel 473 and the second heat insulation panel476 are disposed in the opening in the inner frame 410, and the edge ofthe front panel 471 is attached to the front of the inner frame 410.

Meanwhile, a plurality of heat insulation panels, which are made ofglass, are used, and a predetermined space for reducing heat transfer isformed between the heat insulation panels. Low-emissivity glass may beused to minimize heat transfer through the panel assembly 470.

The space may be in a vacuum state in order to effectively reduce heattransfer. As previously described, however, the space may not be easilyformed, and the external appearance of the panel may be deteriorated bythe vacuum hole. For this reason, a space that is filled with an inertgas, such as argon, may be formed instead of the vacuum space. An inertgas exhibits heat insulation properties superior to those of air.Consequently, a predetermined space that is filled with an inert gas maybe formed between the front panel and a corresponding one of the heatinsulation panels and between the heat insulation panels in order toobtain heat insulation effects.

As previously described, the main door or the sub door of each of therefrigerators according to the embodiments of the present invention maybe selectively changed to a see-through door. Specifically, the maindoor or the sub door may be changed to a see-through door by a specificuser input.

The change to the see-through door may be performed by operating theillumination device 600, which is provided in the storage compartment.When the illumination device 600 in the storage compartment is operated,the interior of the storage compartment is brightened. As a result,light in the storage compartment is transmitted through the door and isemitted to the outside such that a user can see the interior of thestorage compartment from the outside. That is, the user input is inputfor operating the illumination device 600.

Meanwhile, the change to the see-through door may be performed byvarious kinds of user input. In addition, various kinds of sensors maybe used to sense user input.

In this embodiment, the refrigerator may include a knock sensor module500 (see FIG. 10) for sensing a user knock input for changing to thesee-through door as a sound wave.

The knock sensor module 500 may be a sensor for sensing a sound wavetransmitted through a medium. The knock sensor module 500 may beconfigured to sense user input in the case in which the sensed soundwave has a specific vibration pattern.

The knock sensor module 500 includes a microphone 510. This means thatas long as a medium is continuous, the point at which the knock input isperformed and the point at which the knock input is sensed may be spacedapart from each other. That is, this means that, in consideration of thetotal area of a general refrigerator door, the point at which the knockinput is performed and the point at which the knock input is sensed maybe maximally spaced apart from each other as long as the medium of therefrigerator door is continuous. In other words, this means that thepoint at which the knock input is performed and the point at which theknock input is sensed may be different from each other. In particular,this means that the knock input may be performed anywhere on asee-through region of the door. The reason for this is that the entiretyof the see-through region of the door is formed of the same medium.

Here, the point at which the knock input is performed may be a point atwhich user input for changing to the see-through door is performed, andthe point at which the knock input is sensed is a point at which themicrophone 510 senses the input. Consequently, it is possible to usevarious input points and methods by the application of the knock sensormodule 500 irrespective of the posture of the user or whether the useris holding an object in his/her hands. That is, the user generallyperforms a knock input using his/her finger in a comfortable posture,but the user may perform a knock input even while using an object heldin his/her hand according to circumstances. In addition, knock input maybe performed anywhere in a vertically long region such that the user caneasily and conveniently perform knock input irrespective of the heightof the user.

In this embodiment, it is possible for the user to perform input at anyposition on the front of the door by the application of the knock sensormodule 500. In addition, the microphone may be flexibly located so as tocorrespond to any position of the door as long as the same medium iscontinuous between the point at which the knock input is performed andthe point at which the knock input is sensed.

Meanwhile, an acceleration sensor for sensing the vibration of a medium,rather than a sound wave, may be used in order to sense the user knockinput. That is, the acceleration sensor may sense dynamic force, such asacceleration, vibration, or impact, generated by a knock input performedon the front panel, and thereby determine that a predetermined knockinput has been performed. The acceleration sensor may be classified asan inertia type acceleration sensor, a gyro type acceleration sensor, ora silicon semiconductor type acceleration sensor.

In the case in which the acceleration sensor is used, the point at whichthe knock input is performed and the point at which the knock input issensed may be spaced apart from each other as long as the medium of thefront panel is maintained uniform. However, the extent of attenuation ofthe vibration transmitted through the medium is increased as thedistance between the point at which the knock input is performed and thepoint at which the knock input is sensed is increased, due to thecharacteristics of vibration. Even when knock inputs having the sameintensity are performed, therefore, sensing errors may be increased asthe distance between the point at which the knock input is performed andthe point at which the knock input is sensed is increased.

Meanwhile, the refrigerator may vibrate when a refrigerating cycle isperformed. In addition, the refrigerator may vibrate due to a very loudexternal noise or when a heavy object falls onto the floor on which therefrigerator is installed. The acceleration sensor may sense suchexternal vibration as a knock input despite the space between the pointat which the vibration is generated and the point at which the vibrationis sensed and the discontinuity of the media. The reason for this isthat such external vibration may cause vibration of the refrigerator.That is, such external vibration may vibrate the entirety of the door,particularly the front panel.

In this embodiment, therefore, a sound wave transmitted through a mediummay be used instead of vibration of the medium itself or vibrationtransmitted through the surface of the medium. That is, a microphone,rather than an acceleration sensor, may be used.

Even though the medium in the front panel is a solid medium, which isdifferent from air, a sound wave may be effectively transmitted a longdistance due to the characteristics of the sound wave.

For example, a person can know that a train is coming from a longdistance when the person places his/her ear on a railroad track. Thismeans that a sound wave is effectively transmitted a very long distancethrough the medium of the railroad track.

In the acceleration sensor described above, in the same medium, theextent of attenuation of dynamic force is increased as the distancebetween the point at which an input is performed and the point at whichthe input is sensed is increased. On the other hand, the extent ofattenuation of a sound wave is very small. Consequently, it is moreeffective to use a microphone that senses a knock input as a sound wavein consideration of the size of the refrigerator.

Consequently, the knock sensor module 500 senses a user knock inputusing a sound wave transmitted through the front panel. As a result, anadditional device, such as a touch panel, need not be mounted to thefront panel. This means that it is possible to prevent the occurrence ofproblems, such as the increase of cost, complexity, and the reduction ofdurability, attributable to the addition of the touch panel. Inaddition, this means that the knock input may be performed anywhere onthe front panel. Consequently, an additional device for sensing theknock input may be omitted from the see-through region. That is, themicrophone 510 may be located outside the see-through region, wherebythe microphone is prevented from interfering with the see-throughregion.

In this embodiment, the front panel may be a medium through which asound wave generated by a user knock input is transmitted, as previouslydescribed. That is, the user may perform a knock input on the frontpanel, which is exposed from the front of the door, and the microphonemay sense a sound wave transmitted through the front panel.

In the case in which the microphone is used as a sensor for sensing asound wave, the sound wave transmitted through the front panel istransmitted to the microphone via a new medium, e.g. air. Consequently,it is very important to isolate the sound wave transmission spacebetween the medium and the microphone from the outside. The reason forthis is that if such a shielding space or a hermetically sealed space isnot provided, external noise may be input to the microphone. As will bedescribed later, therefore, it is very important to tightly attach themicrophone to the front panel and to maintain the tight contacttherebetween. In addition, it is necessary to continuously apply forceto a support member for supporting the microphone such that the supportmember is in tight contact with the front panel. That is, the supportmember may be tightly attached to the front panel.

In this embodiment, the user may perform knock input on the middle partof the door, which is changed to a see-through region, and the knockinput may be sensed using the microphone provided at the edge of thedoor, which is not changed to a see-through region. Of course, the pointat which the knock input is performed and the point at which the knockinput is sensed are located in the continuous medium of the single frontpanel. The reason for this is that if the medium is changed, the extentof attenuation of a sound wave is increased, whereby sensing accuracymay be reduced.

On the other hand, this means that it is possible to reduce thepossibility of an input applied to a medium other from the front panelbeing determined to be a normal knock input. That is, this means that itis possible to greatly reduce the possibility of determining that animpact applied to a part of the refrigerator other than the front panelis a normal knock input. The reason for this is that the cabinet of therefrigerator is generally not made of the same medium as the frontpanel.

Impact applied to the other parts of the refrigerator may be vibrationof the refrigerator itself. The entirety of the refrigerator may vibratedue to various causes, such as the vibration of the refrigeratorgenerated as the result of a refrigerating cycle being performed or thevibration of the refrigerator generated by external force applied to therefrigerator. In this case, the vibration of the refrigerator may betransmitted through the front panel, with the result that the vibrationsensor may be affected. That is, if large vibration is generated despitethe difference between media, the vibration sensor, which is provided atthe front panel, may recognize the vibration as a normal knock input. Inparticular, the acceleration sensor may malfunction.

As described above, however, the extent of attenuation of a sound wavetransmitted through the different media may be great if the quality ofthe media is not maintained. Consequently, a sound wave generated byimpact applied to a part of the refrigerator other than the front panel(e.g. the cabinet) may be sufficiently attenuated while beingtransmitted through various kinds of media. In the case in which a soundwave is sensed and recognized as a knock input, therefore, it ispossible to greatly reduce the possibility of impact or vibrationapplied to the part of the refrigerator other than the front panel beingrecognized as the knock input. That is, the microphone is less sensitiveto the vibration of the refrigerator than the acceleration sensor.Consequently, it is possible to greatly reduce the possibility ofvibration of the refrigerator being recognized as a normal knock input.

As shown in FIG. 10, the refrigerator according to this embodiment mayinclude a knock sensor module 500, a main controller 700, and anillumination device 600.

The knock sensor module 500 may be provided at the front of the door,for example at the front panel 271 or 471 of the sub door 200 or 400, soas to sense a user knock input.

When the user normally inputs a knock signal for changing to asee-through door, the main controller 700 performs control such that theillumination device 600 is operated. Consequently, the interior of thestorage compartment is brightened, whereby the change to the see-throughdoor is performed.

Specifically, the knock sensor module 500 may include a microphone 510for sensing a knock input as a sound wave. The microphone 510 may sensea sound wave transmitted through the medium of the front panel.

The microphone 510 may sense not only a sound wave generated by the userknock signal but also a sound wave generated by external noise. Thelatter sound wave or vibration may be noise. Consequently, it isnecessary to prevent such noise from being introduced into themicrophone 510. That is, it is necessary to prevent external noise frombeing transmitted to the microphone through the space between the frontpanel and the microphone.

To this end, the microphone 510 may be tightly attached to the medium.In particular, the microphone 510 may be tightly attached to the frontpanel 271 or 471. Consequently, a mounting member or a support memberfor tight attachment of the microphone 510 may be needed. Concreteembodiments of the mounting member or the support member will bedescribed later.

The main controller 700 is a controller for performing general controlof the refrigerator. The main controller may also be called a mainmicrocomputer. That is, the main controller may be a controller forperforming control such that a compressor or various fans are driven ata predetermined temperature.

Meanwhile, the refrigerator generally includes a door switch 800.Whether the door of the refrigerator is open or closed may be sensed bythe door switch 800. When the door is opened, the door switch is turnedon, with the result that an illumination device 610 in the storagecompartment is operated. When the door is closed, the door switch isturned off, with the result that the illumination device 610 in thestorage compartment is not operated. Of course, the door switch may beturned on and off in the opposite manner. The operation of the doorswitch 800 and the illumination device 610 may be performed irrespectiveof the controller 700. Of course, the controller 700 may check theclosed and open states of the door through the door switch 800, and maycontrol the illumination device 610 based thereon.

In this embodiment, the door switch 800, the main controller 700, andthe illumination device 600 may be controlled in two aspects.

First, an example in which the main door is changed to a see-throughdoor will be described.

The main controller 700 may operate the illumination device 600,particularly a main illumination device 610, for changing to thesee-through door. The change to the see-through door may be performed onthe premise that the main door is closed. Consequently, the maincontroller 700 may perform control such that the main illuminationdevice 610 is operated even in the state in which the door switch 800 ison (in the state in which the door is dosed) based on the determinationof a normal knock signal. In addition, the operation of the mainillumination device 610 may be controlled through a see-through doorchange algorithm as long as the door is not opened. For example, themain illumination device may be controlled so as to be graduallybrightened. In addition, the main illumination device may be controlledso as to be stopped after a predetermined amount of time. That is, theillumination device may be controlled so as to be turned off after apredetermined amount of time.

When the door is opened during the change to the see-through door,switching to a general control algorithm for controlling the mainillumination device 610 may be performed. That is, the main illuminationdevice 610 may be controlled so as to be continuously operated in thestate in which the main door is open. Of course, control may beperformed such that if the main door is open for an excessive amount oftime, an alarm is generated, and the main illumination device 610 isturned off.

Next, an example in which the sub door, rather than the main door, ischanged to a see-through door will be described. In this case, a subillumination device 620 for illuminating the interior of the sub storagecompartment may be provided in addition to the main illumination device610, which illuminates the interior of the storage compartment.

Although not shown, the sub illumination device 620 may include an LEDmodule mounted to one side or each side of the opening 115 or 215 of themain door 100 to illuminate the sub storage compartment. The LED modulemay include a plurality of LEDs arranged on a vertically long circuitboard at predetermined intervals.

The LED module may be mounted in a groove formed in each side of theopening in the main door 100, and may be covered by a transparent cover,which protects the interior of the LED module and prevents moisture orforeign matter from being introduced into the LED module.

The main controller 700 may operate the sub illumination device 620 tochange the sub door to the see-through door in response to adetermination of a normal knock signal. At this time, the subillumination device 620 may be controlled to be operated for apredetermined amount of time. Even when the user opens the sub door, thesub illumination device 620 may be controlled to be continuouslyoperated within the predetermined amount of time.

On the other hand, the user may open the main door, rather than the subdoor, within the predetermined amount of time. At this time, it is notnecessary to maintain the state in which the sub door is changed to thesee-through door. Upon sensing the opening in the main door through thedoor switch during changing of the sub door to the see-through door,therefore, the main controller 700 may perform control such that theoperation of the sub illumination device 620 is stopped.

Consequently, it is possible to reduce unnecessary operation of theillumination device 600 based on the control relationship among the maincontroller 700, the illumination device 600, and the door switch 800.

The main controller 700 may determine whether a signal input through theknock sensor module 500 is a normal knock signal. That is, the maincontroller 700 may directly determine whether the input signal is aknock signal or noise. In this case, however, the main controller 700may be overloaded, and the amount of noise in a signal line may befurther increased due to the distance between the vibration sensor 500and the main controller 700.

As previously described, the microphone 510 may be provided at the frontpanel 271 or 471. In many cases, however, the main controller 700 isgenerally provided at one side of the cabinet 10, rather than the door.As a result, the distance between the microphone 510 and the maincontroller 700 is increased, which means that the length of a signalline is increased. This means that a normal knock signal may be input tothe main controller 700 in the state of having been deteriorated due tothe noise in the signal line. As a result, a knock signal recognitionrate may be reduced. In particular, the unit of a signal output from themicrophone is mV, whereas the unit of a signal input to the maincontroller 700 is V. Consequently, it is not desirable for the maincontroller 700 to determine a knock input due to the difference insignal amplitude.

In particular, the refrigerator is an electronic device using highvoltage and high current. Consequently, the amount of electrical noisethat is generated is relatively large. This means that a signal having aunit of mV output from the microphone has low resistance to electricalnoise.

In order to solve this problem, according to this embodiment, amicrophone and a module microcomputer are modularized to constitute theknock sensor module.

The knock sensor module, denoted by reference numeral 500, may include amicrophone 510 and a module microcomputer 540. As previously described,the microphone 510 may be a sensor for sensing a knock input, and themodule microcomputer 540 may be provided to determine whether the knockinput is a normal knock input based on the signals sensed by themicrophone 510 and to generate a knock-on signal.

For example, upon determining that the knock input is a normal knockinput, the module microcomputer 540 may transmit a signal indicatingthat a normal knock input has been performed (a knock-on signal) to themain controller 700. Upon determining that the knock input is not anormal knock input, the module microcomputer 540 may not transmit theknock-on signal to the main controller 700. For example, upondetermining that the knock input is a normal knock input, the modulemicrocomputer 540 may transmit a knock-on signal of 5 V to the maincontroller 700. Upon determining that the knock input is not a normalknock input, the module microcomputer 540 may transmit a signal of 0 Vto the main controller 700. In the latter case, no signal is transmittedto the main controller.

The main controller 700 receives only the knock-on signal. Consequently,the main controller 700 does not perform any additional determination.As a result, it is possible to minimize the amount of noise in thesignal line between the module microcomputer 540 and the main controller700. In the same manner, the module microcomputer 540 may receive asignal having minimized noise through the modularized microphone todetermine whether knock-on has been performed. Consequently, it ispossible to secure a recognition rate with high accuracy.

Meanwhile, the knock sensor module 500 may include a filter 520. Thefilter 520 may remove noise from a signal received from the microphone510. Specifically, the filter 520 may be a DC noise filter. The filteredsignal may be amplified by an amplifier 530. Consequently, the knocksensor module 500 may further include an amplifier 530 for amplifyingthe filtered signal and transmitting the amplified signal to the modulemicrocomputer 540. Specifically, the amplifier 530 may be an OPamplifier.

In the knock sensor module 500, the filter 520, the amplifier 530, andthe module microcomputer 540 may be mounted on a single printed circuitboard (PCB) 545, and the microphone 510 may be connected to the PCB 545via a signal line 516. Consequently, the knock sensor module 500,particularly the PCB 545, may be configured to be smaller than the maincontroller 700. This means that the PCB 545 may be mounted at a positionadjacent to the position at which the microphone 510 is mounted.Consequently, the length of the signal line 516 between the microphone510 and the PCB 545 may be relatively short. This means that it ispossible to effectively prevent noise from being introduced through thesignal line 516.

A structure in which the microphone 510 is mounted or fixed will bedescribed later.

Hereinafter, a microphone or a microphone module will be described indetail with reference to FIG. 11.

As shown in FIG. 11, a microphone may be provided as a microphone module510. That is, a microphone 511 for directly sensing a sound wave may bereceived in a microphone receiving part 512. The assembly of themicrophone 511 and the microphone receiving part 512 may be referred toas a microphone module 510, or simply as a microphone 510.

The microphone 511 may be formed in a circular shape having apredetermined thickness. The microphone 511 may be received in themicrophone receiving part 512. The movement of the microphone 511 islimited by the internal shape of the microphone receiving part 512. Thatis, the microphone may be supported so as to be suspended in themicrophone receiving part 512.

The microphone receiving part 512 may be made of an elastic material,such as rubber. Basically, the microphone 511 may tightly contact themicrophone receiving part 512. The microphone receiving part 512 may beprovided in the upper and lower ends thereof with openings 514 and 515.The openings may be circular.

One surface of the microphone 511 may be a sound wave receiving part 511a, which may be directed toward a specific one of the openings. For thesake of convenience, the sound wave receiving part 511 a is directedtoward the lower opening 514, as shown in FIG. 13.

The signal line 516 is connected to the other side of the microphone511. As previously described, the signal line 516 may be connected tothe PCB 545 through the opening 515.

A predetermined space may be formed between the lower opening 514 andthe sound wave receiving part 511 a. The space may be sealed. The loweropening 514 may come into tight contact with the medium, e.g. the frontpanel 271 or 471, so as to seal the space 515.

The space 517 may be isolated from the upper opening 515 as the resultof tight contact between the microphone 511 and the microphone receivingpart 512.

In order to prevent damage to the tight contact space due toeccentricity, a protrusion 513 may be formed along the circumference ofthe lower opening 514. That is, the sealed space may be effectivelymaintained due to elastic deformation of the protrusion 513 even whendeviation of force pushing the microphone 511 so as to tightly contactthe microphone receiving part 512 is generated later.

Consequently, one side of the tight contact space is sealed by themedium. A sound wave transmitted through the medium may be received bythe microphone 511 through air in the space.

The introduction of external noise or vibration into the space isminimized due to the sea. As a result, it is possible to greatly reduceerrors in knock-on determination due to external noise and malfunctionand to very accurately secure a knock-on recognition rate. That is,accuracy in determining a knock-on input as knock-on when the knock-oninput is performed may be remarkably improved.

Hereinafter, a structure in which the vibration sensor is mounted willbe described in detail. In particular, in the microphone module 510shown in FIG. 11, a structure in which the vibration sensor is mountedwill be described in detail. For the sake of convenience, the signalline 516 is not shown.

First, an embodiment of a structure in which the microphone module 510is mounted will be described with reference to FIG. 12.

This embodiment may be applied to an embodiment in which the front panel271 defines the middle part of the door or the sub door and the edge ofthe door or the sub door is defined by the door frame 205.

Specifically, FIG. 12 is a partially cutaway perspective view and anenlarged view showing a structure in which the microphone module 510 ismounted to the sub door. In the enlarged view, the door liner 280 is notshown for the sake of convenience.

According to this embodiment, the microphone module 510 may be tightlymounted to the front panel 271.

As shown, the edge of the front panel 271 is covered by the door frame205, particularly the external door part 210. The microphone module 510is disposed between the external door part 210 and the front panel 271.The microphone module 510 may be tightly mounted to the front panel 271.

Specifically, a support member 550 for tightly mounting the microphonemodule 510 to the front panel 271 may be provided. The support member550 may be provided between the external door part 210 and the frontpanel 271. In addition, the support member 550 may be provided betweenthe external door part 210 and the door decoration part 220.

Consequently, the microphone module 510 or the support member 550 may beprovided outside the opening 211 in the see-through door in the radialdirection. As a result, the microphone module 510 and the support member550 may not be visibly exposed from the front of the door irrespectiveof changes to the see-through door. In addition, the external appearanceof the door is aesthetically improved since the microphone module andthe support member are not visibly exposed.

Specifically, the support member 550 may include an elastic member 555.The elastic member 555 may generate elastic force in the direction inwhich the microphone module 510 is tightly attached. Consequently, forcemay be continuously applied to the microphone module 510 in thedirection in which the microphone module 510 is tightly attached.

The support member 550 may include a rotary shaft 551, a first extensionpart 552 extending from one side of the rotary shaft 551, and a secondextension part 554 extending from the other side of the rotary shaft551. The rotary shaft 551 may be mounted between the external door part210 and the door decoration part 220.

The first extension part 552 may be provided with a holder 553. Theholder 553 may be provided at the rear of the first extension part 552.In addition, the microphone module 510 may be mounted in the holder 553.

The elastic member 555 may be mounted between the second extension part554 and the door decoration part 220. The elastic member generateselastic force for pushing the second extension part 554 forward. Theelastic force is converted into force for pushing the first extensionpart 552 rearward like a seesaw. As a result, the microphone module 510comes into tight contact with the front panel 271 through the holder553. Consequently, force is continuously applied through the elasticmember 555 in the direction in which the microphone module 510 comesinto tight contact with the front panel 271.

If the sub door 200 does not include the door decoration part 220 andthe inner frame 230, the support member 550 may be mounted between theexternal door part 210 and the door liner 280. In any case, therefore,the support member may be located outside the opening in the door frame205 in the radial direction.

The elastic member 550 may be a spring, and a protrusion for supportingthe elastic member 550 may be provided at the rear of the secondextension part 554.

Specifically, the elastic member 550 may be compressed to apredetermined length during assembly to generate elastic force forpushing the second extension part 554.

Since the elastic member 550 pushes the second extension part 554, thefirst extension part 552, which is located at the opposite side of therotary shaft 551, pushes the microphone module 510 such that themicrophone module 510 comes into tight contact with the front panel 271.That is, the state in which the microphone module 510 is tightlyattached to the front of the front panel 271 may be continuouslymaintained.

Consequently, the microphone module 510 may effectively recognize thatthe user knocks the front panel 271.

Hereinafter, another embodiment of the structure in which the microphonemodule 510 is mounted will be described with reference to FIGS. 13 and14.

In this embodiment, the microphone module 510 may be tightly attached tothe front panel, in the same manner as in the previous embodiment. Inaddition, the microphone module 510 may be mounted to the door framesuch that the microphone module 510 does not interfere with thesee-through door.

The structure in which the microphone module 510 is mounted according tothis embodiment may be applied to the door shown in FIG. 6. That is, thestructure according to this embodiment may be applied to the case inwhich the front panel 471 forms the entire external appearance of thefront of the door.

Specifically, the structure according to this embodiment may be appliedto a door characterized in that a heat insulation panel is inserted intoan opening and the rear edge of a front panel is tightly attached to adoor frame.

As previously described, the door frame 405 may include an inner frame410. The inner frame 410 may be integrally formed with cap decorationparts 460, or the cap decoration parts 460 may be coupled to the upperand lower parts of the inner frame 410.

In FIGS. 13 and 14, the microphone module 510 is mounted through the capdecoration part 460 located at the upper part of the door.

More specifically, the cap decoration part 460 may be provided in thefront thereof with a through hole 461, through which the microphonemodule 510 extends. The microphone module 510 may extend through thethrough hole 461 so as to be tightly attached to the front panel 471.That is, the microphone module 510 may be tightly attached to the rearof the front panel 471.

A support member for tightly attaching the microphone module 510 may beprovided. The cap decoration part 460 may be provided with a locationpart 462, in which the support member 560 is located.

At least a portion of the microphone module 510 is received in a holder561. Consequently, the holder 561 may be pushed toward the front panel471 such that the microphone module 510 is tightly attached to the rearof the front panel 471 and such that the tight contact therebetween ismaintained. Consequently, the support member may include an elasticmember 562 for elastically supporting the holder 561 and applyingelastic force in the direction in which the holder 562 is pushed.

The holder 561 may be provided with a slit or slot 561 a, through whichthe signal line 516 shown in FIG. 13 is withdrawn. That is, themicrophone module may be received in the holder 561, and the signal line516, which transmits the signal received from the microphone module tothe outside, may extend to the outside of the holder 561 through theslit or slot 561 a.

In the case in which the holder 561 is made of an elastic material, thesignal line 516 may be stably supported in the state of extendingthrough the slit or slot 561 a.

The support member 560 may include a holder receiving part 563 forreceiving the holder 561. The elastic member 562 may be interposedbetween the holder 561 and the holder receiving part 563. Consequently,force pushing the holder 561 forward may be continuously applied to theholder 561 from the holder receiving part 563.

Meanwhile, the holder receiving part 563 may be located in the locationpart 462 such that force pushing the holder receiving part 563 forwardis continuously applied to the holder receiving part 563. That is, thesupport member 560, which includes the holder receiving part 563, may belocated in the location part 462 such that the support member 560 ismounted in position and such that force pushing the support member 560forward is automatically applied to the support member 560.

To this end, a cover 465 for covering the location part 462 may beprovided. The cover may be a hinge cover 465 for covering the sub doorhinge 130, which is mounted to the cap decoration part 460. That is, thesupport member may be pushed forward and supported as the hinge cover465 is coupled to the cap decoration part 460.

Specifically, the cover 465 may be coupled to the cap decoration part460 through a hook structure 465. At this time, the support member 560may be pushed forward and fixed by a protrusion or rib 467 formed at thecover 465.

Consequently, the protrusion or rib 467 may push the entirety of thesupport member 560 forward, and may maintain this state. In addition,the elastic member 562 continuously pushes the holder 561 forward. As aresult, the microphone module 510 remains in tight contact with thefront panel 471. Of course, in this embodiment, the microphone module510 may come into tight contact with the rear of the front panel 471through the through hole 461.

The shape of the through hole 461 may correspond to that of the holder561. Consequently, it is possible to prevent the holder 561 from movingin the through hole 461, thereby effectively maintaining the state inwhich the microphone module 510 is in tight contact.

Meanwhile, the PCB of the knock sensor module 500 may be mounted at thebottom of the cover 465. That is, the cap decoration part 460 may beprovided with a space in which the sub door hinge and PCB are mounted.The signal line of the knock sensor module 500 may extend into thecabinet 10 or the main door through a through hole 131 in the sub doorhinge 130 so as to be connected to the main controller 700.

In order to arrange the signal line, therefore, the knock sensor module500 may be mounted at the upper cap decoration part, although the knocksensor module 500 may be mounted at any position at the edge of the dooror the sub door.

Hereinafter, another embodiment of the structure in which the microphonemodule 510 is mounted will be described with reference to FIGS. 15 and16.

In this embodiment, the microphone module 510 is mounted using the doorframe, particularly the cap decoration part 460, in the same manner asin the previous embodiment.

The cap decoration part 460 may be provided with a through hole 461. Themicrophone module 510 may come into tight contact with the rear of thefront panel 471 through the through hole 461.

In the state in which the microphone module 510 is received in a holder561 identical or similar to that of the previous embodiment, the holder561 may continuously push the microphone module 510 toward the frontpanel such that the microphone module 510 remains in tight contact withthe front panel.

The holder 561 may be made of an elastic member. Consequently, theholder 561 may be compressed so as to have elastic restoring forcetoward the front panel.

To this end, a holder mounting part 463 may be formed in the rear of thethrough hole 461. The holder 561 may be pushed and mounted in the holdermounting part 463 in the state of receiving the microphone module 510.The through hole 461 may be formed in the direction in which the holderis mounted so as to be larger than the holder 561. That is, in the casein which the holder 561 is pushed and mounted from the left side to theright side, as shown in FIG. 16, the leftward-rightward width of thethrough hole 461 may be larger than that of the holder 561. Of course,the upward-downward width of the through hole 461 may be equal to thatof the holder 561 such that the upper and lower parts of the holder cancome into tight contact with the through hole 461.

Specifically, a predetermined space 464 is formed between the holdermounting part 463 and the through hole 461. The holder 561 may be fittedinto the space. More specifically, the forward-rearward width of thespace is gradually reduced as the holder 561 is further inserted. Thatis, in the state in which the holder 561 is maximally inserted, theholder 561 is compressed in the forward-rearward direction.Consequently, the holder 561 has elastic restoring force, by which theholder 561 continuously pushes the microphone module 510 forward.

Meanwhile, in the state in which the holder 561 is maximally inserted,the holder 561 may be fixed by the cover 465. As previously described,the cover 465 is a cover for covering the cap decoration part 460 or ahinge cover for covering the sub door hinge 130. The cover 465 may becoupled to the cap decoration part 460 by a hook 466.

As shown in FIG. 17, the cover 465 may be provided at the bottom thereofwith a protrusion or rib 467 protruding downward. When the cover 465 iscoupled to the cap decoration part 460, the protrusion or rib 467 pushesone side of the holder 561. That is, the protrusion or rib 467 pushesone side of the holder 561 in the direction in which the holder 561 isinserted through the through hole 461.

Consequently, the holder 561 remains compressed in the holder mountingpart 463, whereby the holder may be securely fixed irrespective ofvibration or movement of the door. As a result, the microphone 510 maybe tightly attached to the front panel 471, and this state may becontinuously maintained.

In other words, as the holder 561 is correctly inserted into the throughhole 461, the holder 561 is compressed in the forward-rearwarddirection. The rib 467 is provided to fix the holder 561 in position.Unless the rib 467 is removed, therefore, the holder 561 is fixed by thefront panel, the rib 467, and the holder mounting part 463 in the stateof being compressed, and this state may be maintained.

FIG. 18 is a conceptual view showing the position of a see-through doorat which the microphone module is mounted and the region of thesee-through door in which a user performs a knock input. When the maindoor or the sub door is configured so as to be changed to a see-throughdoor, the door has therein an opening 211 or 411. Consequently, theinterior of the storage compartment or the sub storage compartment maybe seen from the outside through the inner region of the opening in theradial direction.

As previously described, the inner region and a portion of the outerregion of the opening in the front of the door may be regions defined bythe front panel. As previously described, in the outside type door, theinner region and a portion of the outer region of the opening in thefront of the door are defined by the front panel, and the edge of thedoor is defined by the door frame. In the inside type door, the entiretyof the front of the door may be defined by the front panel.

Basically, therefore, a region in which a user knock input is performedmay be the entirety of the region defined by the front of the frontpanel. Conceptually, however, a user knock input may be performedthrough a portion that is changed to the see-through door. The portionthat is substantially changed to the see-through door may be the innerportion of the opening 211 or 411 in the radial direction. Consequently,the entirety of the inner area of the quadrangle defined by the opening211 or 411 may be defined as a region in which a user knock input may beperformed.

Since the knock input region is a see-through region, the microphonemodule may be mounted outside the knock input region. Of course, theregion in which the microphone module is mounted may be a portion of thefront panel extending in the radial direction.

Consequently, the region in which the microphone module is mounted maybe outside the opening 211 or 411 in the radial direction. As shown inFIG. 18, the microphone module may be mounted in a hatched region Ssurrounding the opening.

Since the region S is not a see-through region, the user cannot easilyrecognize the microphone module from the front of the door, even thoughthe microphone module is tightly attached to the front panel. That is,the microphone module does not interfere with the see-through region. Asa result, it is possible to effectively enlarge the region in which aknock input can be performed. On the other hand, it is possible tosufficiently increase the distance between the knock input region andthe region in which the microphone module is mounted. In addition, it ispossible to achieve a more vivid and pleasing appearance through thesee-through region.

Meanwhile, in order to sufficiently prevent the microphone module frombeing visually exposed from the front of the door, a printed layer maybe formed on the rear of the region S. That is, a printed layer may beformed on the rear of the front panel corresponding to the region S. Inthe outside type door, however, the region S is covered by the doorframe or the external door part, whereby the printed layer may beomitted.

As previously described, a user input for changing to the see-throughdoor may be a knock input, which may be sensed by the microphone.

Meanwhile, the front of the door may be vibrated by variousenvironmental factors. The front of the door may be vibrated by impactwhen the door is opened and closed or by strong external noise. Inputsgenerated by environmental factors may be determined to be knocksignals.

When the user taps on the front of the door a plurality of times, it maybe determined to be a normal knock input. More specifically, when theuser taps on the front of the door a plurality of times at predeterminedtime intervals, it may be determined to be a normal knock input.

For example, when the user taps on the front of the door twice within apredetermined time, it may be determined to be a normal knock input. Theresults of analysis of normal user knock patterns show that the timeinterval between a first knock and a second knock is about 600 ms orless. That is, since 1 second is 1000 ms, when a first knock and asecond knock are performed at an interval of less than 1 second, it maybe determined to be a normal knock input.

Consequently, it is possible to prevent an abnormal input from beingdetermined to be a knock signal by setting the time interval.

Meanwhile, the magnitudes of knocks performed by users may be differentfrom each other. Since the media are the same, however, the vibrationpattern deviation is very small, even though the deviation in magnitudeis large. Consequently, the magnitude deviation of the knocks may beoffset through an algorithm, and therefore it is possible to effectivelyrecognize a normal knock input using a knock input pattern and the timeinterval between knocks as factors. This means that it is possible togreatly reduce the possibility of recognizing an abnormal input as aknock input.

As previously described, upon determining that a knock input has beenperformed, the controller 700 operates the illumination device 600. Thecontroller 700 may perform control such that the illumination device 600is turned off after a predetermined amount of time. In the case in whichanother knock input is performed before the predetermined amount oftime, the controller 700 may perform control such that the illuminationdevice 600 is turned off. The knock input at this time may be the sameas a knock-on input, and a single knock input may be performed as aknock off input in order to distinguish between the knock off input andthe knock-on input.

Of course, such a single knock input may be recognized within apredetermined time after the determination of knock-on.

As previously described, the entirety of the front of the door may besubstantially formed as a knock-on input region through the use of themicrophone. That is, a large region may be formed as a knock-on inputregion without mounting an additional sensor, such as a touch sensor oran electrostatic sensor, in the knock-on input region. This means thatit is possible to prevent the increase of cost due to the touch sensoror the electrostatic sensor and an additional panel including the sameand to improve durability. In addition, the structure of the door may begreatly simplified.

In addition, this means that it is possible to easily perform a knock-oninput through a large region irrespective of the posture of the user orthe freedom of the hands of the user. Furthermore, it is possible toform the knock-on input region so as to be substantially identical tothe see-through region. Consequently, it is possible to omit an elementthat blocks the transmission of light, e.g. a touch panel, from thesee-through region. Consequently, it is possible to realize a moreunobstructed see-through region.

In the above embodiments, a user knock-on input is recognized using themicrophone module so as to achieve a change to the see-through door.Specifically, a knock-on input performed on the front panel isrecognized using the knock sensor module.

More specifically, a knock-on input is not recognized using only themicrophone or the microphone module, and a knock sensor module includingthe same and a controller are separately provided. Consequently, it ispossible to reduce the load of the main controller and to minimize theamount of noise that may be generated in the signal line between themain controller and the knock sensor module. That is, noise is minimizedthrough modularization. In addition, the microphone module is tightlyattached to the medium, on which a knock input is performed, whereby itis possible to minimize the effects caused by external noise.

The refrigerator may be generally installed in a kitchen, in whichexternal noise may be occasionally generated. For example, externalnoise of 90 dB or higher may be generated. In the case in which suchexternal noise is generated at a particular interval, this externalnoise may be incorrectly recognized as a knock-on input. That is, evenin the case in which a user knock input is not performed, a knock basedon external noise similar to a knock input may be applied to the frontpanel. In this case, since the refrigerator is automatically changed tothe see-through door, the user may incorrectly deduce that therefrigerator is out of order. Consequently, it is necessary to provide amethod of further reducing such a possibility.

Hereinafter, embodiments that are capable of greatly reducing incorrectrecognition due to external noise in cooperation with theabove-described basic embodiments will be described in detail.

FIG. 19 is a block diagram showing an embodiment having a correctionsensor for removing the effects caused by external noise.

This embodiment is characterized by further including a microphone ormicrophone module for sensing external noise. That is, this embodimentis characterized by further including an additional microphone ormicrophone module as a correction sensor for removing the effects causedby external noise.

The structure or operation of the microphone or microphone module may beidentical or similar to that of the microphone or microphone moduledescribed with reference to FIGS. 10 and 11.

Specifically, in this embodiment, additional hardware is included toremove the effects caused by external noise.

As shown in FIG. 19, a microphone 510 a or a microphone module as acorrection sensor may be provided to sense external noise. Themicrophone 510 a may be referred to as a second microphone. In additionto the second microphone, a second microphone receiving part identicalor similar to that of the microphone 510 described above may be providedto constitute a second microphone module.

There is no necessity for the microphone 510 a serving as the correctionsensor to be tightly attached to the front panel in order to senseexternal noise. That is, it is sufficient to mount the microphone 510 aserving as the correction sensor at any particular point of therefrigerator. The microphone 510 a serving as the correction sensor maybe referred to as a second microphone.

When a knock-on input is performed or external noise is generated, themicrophone 510 for sensing the knock-on input and the microphone 510 afor sensing the external noise sense sound waves. The sensed sound wavesare subtracted by a subtractor 570. That is, the signal sensed by thesecond microphone 510 a may be subtracted from the signal sensed by themicrophone 510. Consequently, the effects of the external noise may beremoved using two microphones.

For example, external noise that is very similar to a knock-on input maybe generated. In this case, it may be incorrectly recognized as aknock-on input if only the microphone 510 is provided. In the case inwhich two microphones 510 and 510 a are used, however, the microphonesmay recognize external noise that is very similar to the knock-on input.Consequently, it is possible to substantially remove the effects of theexternal noise by subtracting the signals sensed by the microphones.

The signal having passed through the subtractor 570 is input to themodule microcomputer 540 via the amplifier 530. The module microcomputer540 determines whether the input signal is a knock-on signal. That is,in this embodiment, the module microcomputer 540 is operated in the samemanner as in the previous embodiment. In addition, the signals sensed bythe microphones may be provided to the subtractor 570 after passingthrough filters 520 and 520 a.

According to this embodiment, therefore, the effects of the externalnoise are removed, whereby it is possible to more correctly performknock-on recognition.

As previously described, the position of the second microphone 510 a forsensing the external noise is not particularly restricted. However, thesecond microphone 510 a for sensing the external noise and themicrophone 510 for sensing the knock input may be modularized into asingle module. For this reason, the second microphone 510 a may beprovided adjacent to the microphone 510. That is, the microphone 510 andthe second microphone 510 a may be connected to a single PCB via twosignal lines. Of course, there is no necessity for the second microphoneto be tightly attached to the front panel. As will be described later,the second microphone 510 a may be disposed in the space between the capdecoration part 460 and the cover 465.

Meanwhile, in this embodiment, the effects of external noise are removedusing the additional hardware, i.e. the subtractor. Of course, in thisembodiment, the microphone 510 a and the subtractor 570 may be providedas a single module.

FIG. 20 is a block diagram showing another embodiment for removing theeffects caused by external noise.

This embodiment is very similar to the embodiment shown in FIG. 19. Inthis embodiment, however, the effects of external noise are removedusing the module microcomputer 540. That is, the module microcomputer540 receives both an external noise and a knock-on signal, and removesthe effects of the external noise through an algorithm.

That is, the module microcomputer 540 receives signals sensed by twomicrophones, and executes an algorithm for removing a noise source tofind a knock-on input. For example, the module microcomputer 540 mayexecute an algorithm similar to a subtractor function.

In this embodiment, the effects of the external noise are removed usingsoftware. Consequently, a greater variety of algorithms, such as that ofthe subtractor, may be executed than when implemented using hardware.For example, when the magnitude of external noise is very large, it ispossible to interrupt a knock-on function. That is, when the magnitudeof signals received by the module microcomputer 540 is very large (i.e.when the amount of external noise is too large), it is possible tointerrupt a knock-on function.

In the above embodiments, an additional microphone or microphone modulefor directly sensing external noise is included to minimize the effectscaused by the external noise.

Hereinafter, an embodiment including a human body sensor as an exampleof a correction sensor for removing the effects of external noise willbe described.

The human body sensor is a sensor for sensing whether a user hasapproached the refrigerator. That is, the human body sensor is a sensorhaving no relationship to sound waves.

First, a knock-on input is performed by the user. Consequently, the usermust approach the refrigerator in order to perform a knock-on input.That is, the user approach to the refrigerator is of course required inorder to perform a normal knock-on input. When an input similar to aknock-on input is generated due to external noise, therefore, the inputmay be disregarded.

Specifically, the human body sensor may be one selected from among anultrasonic sensor, a passive infrared (PIR) sensor, an IR sensor, and animage sensor. That is, any sensor that is capable of sensing the motionof the user may be used. Specifically, the human body sensor may be asensor for sensing variation in the motion of the human body. Theabove-mentioned sensors are obvious to those skilled in the art, andtherefore a detailed description thereof will be omitted.

According to this embodiment, a normal knock-on signal may be generatedin the case in which both a human body sensing condition, determined bythe human body sensor, and a knock input condition, determined by theknock sensor module, are satisfied. When the normal knock-on signal isgenerated, the main controller may perform control such that theillumination device is operated. Of course, the main controller mayperform control such that the illumination device is operated only whenboth a normal knock-on signal and a human body sensing signal aregenerated.

As shown in FIG. 21, a human body sensor 510 b serving as a correctionsensor may constitute a module together with the knock sensor module500. The human body sensor 510 b may provide a signal indicatingvariation in the motion of the human body to the module microcomputer540, which may determine than the user has approached the refrigerator.

Consequently, the module microcomputer 540 may determine that both thehuman body sensing condition and the knock input condition aresatisfied, and may generate a knock-on signal. In this case, the humanbody sensor is provided separately from the main controller 700, wherebyit is possible to prevent overload of the main controller 700.

In addition, the human body sensor 510 b may be positioned adjacent tothe knock sensor module 500 shown in FIG. 1. That is, the human bodysensor 510 b may be provided at the front of the door of therefrigerator. Consequently, it is possible to realize a single knocksensor module 500 including the human body sensor, thereby achievingease of installation and cost reduction.

Of course, the human body sensor 510 b may be directly connected to themain controller. That is, the main controller 700 may receive a knock-onsignal from the knock sensor module 500 and a user approach signal fromthe human body sensor 510 b. At this time, the main controller mayperform control such that the illumination device 600 is turned on onlywhen both conditions are satisfied.

For example, the main controller may receive a knock-on signal based onexternal noise. At this time, the main controller cannot receive theuser approach signal from the human body sensor. Consequently, the maincontroller ignores the knock-on signal and prevents the illuminationdevice from being turned on.

That is, it is possible to remove the effects of external noise usingthe human body sensor irrespective of whether the human body sensor isincluded in the knock sensor module or whether the human body sensor isconnected to the main controller. Here, the removal of the effects ofexternal noise may mean that the abnormal determination of externalnoise as a knock-on input is prevented. Of course, this may mean that,even when determination as a knock-on input is abnormally made, theillumination device is prevented from being turned on.

Industrial applicability has been described in the best mode.

A fundamental object of the present invention is to solve the aboveproblems.

An embodiment of the present invention provides a refrigeratorconfigured such that at least a portion of a door for opening andclosing a storage compartment is transparent such that the interior ofthe storage compartment can be seen without opening the door.

An embodiment of the present invention provides a refrigerator includinga see-through door, through which light is transmitted, i.e. arefrigerator configured such that the interior of the storagecompartment can be seen through the door from outside the door.

An embodiment of the present invention provides a refrigerator having aselectively variable see-through door, i.e. a refrigerator configuredsuch that a storage compartment cannot usually be seen through a doorbut such that the storage compartment can be seen through the door asneeded.

An embodiment of the present invention provides a refrigeratorconfigured such that user input for changing to a see-through door iseasily performed and such that the external appearance of therefrigerator, particularly the external appearance of the front of thedoor, is not deteriorated by a user input structure.

An embodiment of the present invention provides a refrigeratorconfigured such that the incidence of error in user input for changingto a see-through door, recognition error, or malfunctions can bereduced. In addition, an embodiment of the present invention provides arefrigerator configured such that the user input recognition rate isincreased.

An embodiment of the present invention provides a refrigeratorconfigured such that a user's tap on a door is effectively sensed so asto change to a see-through door, thereby improving convenience in use.

An embodiment of the present invention provides a refrigeratorconfigured such that a user's tap on a door is effectively sensed evenwhen the position of the door on which the user taps and the position atwhich the user's tap is sensed are spaced apart from each other.

An embodiment of the present invention provides a refrigeratorconfigured such that the position of a door on which a user may tap issubstantially extended to the entirety of the front of the door via thetransmission of a sound wave through a medium.

An embodiment of the present invention provides a refrigeratorconfigured such that a knock input is effectively sensed while thestructure of the refrigerator is simplified to the exclusion of anexpensive device, such as a touch panel.

An embodiment of the present invention provides a refrigeratorconfigured such that heat insulation performance is secured and a dooris stable and easy to manufacture.

An embodiment of the present invention provides a refrigerator includinga door having a black panel, such as a TV or a computer monitor, whereinthe door is changed to a see-through door using illumination as needed,thereby reducing energy consumption for changing to the see-throughdoor.

An embodiment of the present invention provides a refrigeratorconfigured such that the entirety of a see-through region of a door isset to a knock input region and such that a microphone module is mountedoutside the see-through region to prevent the see-through region and themicrophone module from overlapping each other, thereby providing anaesthetically pleasing appearance.

An embodiment of the present invention provides a refrigerator includinga knock sensor module constituted by a microphone module and a modulemicrocomputer to effectively remove noise generated in a signal linebetween a controller for controlling an illumination device and theknock sensor module.

An embodiment of the present invention provides a refrigerator that iscapable of effectively preventing external noise, external impact, andvibration of the refrigerator from being incorrectly recognized as knockinput. In particular, an embodiment of the present invention provides arefrigerator including a correction sensor that is separate from avibration sensor or a knock sensor module to effectively preventnegative effects caused by external disturbance.

An embodiment of the present invention provides a refrigerator includinga microphone module as an example of a correction sensor for effectivelypreventing effects caused by external disturbance.

An embodiment of the present invention provides a refrigerator includinga human body sensor as an example of a correction sensor for effectivelysolving problems caused when a knock sensor module recognizes anexternal disturbance as a knock input.

In accordance with an aspect of the present invention, the above andother objects can be accomplished by the provision of a refrigeratorincluding a cabinet having a storage compartment therein, anillumination device for illuminating the interior of the storagecompartment, a door hinged to the cabinet for opening and closing thestorage compartment, the door having an opening formed therein, a panelassembly provided at the door, the panel assembly having a front panelprovided at the front of the door, a knock sensor module including amicrophone for sensing a knock input applied to the door as a soundwave, and a controller for operating the illumination device such thatlight is transmitted through the panel assembly when the knock input issensed, whereby the interior of the storage compartment can be seenthrough the opening from outside the door.

The controller may be provided separately from the knock sensor module.In particular, the controller may be provided separately from the modulemicrocomputer. That is, the module microcomputer directly determineswhether the knock input sensed by the microphone is a normal knockinput. Consequently, it is possible to prevent overload of thecontroller. In addition, it is possible to reduce the length of aconnection line or a signal line between the microphone and the modulemicrocomputer, whereby it is possible to greatly reduce the effects ofexternal noise introduced into the connection line or a signal line.

A microphone receiving part for receiving the microphone may be providedin order to constitute a microphone module together with the microphone.

The knock sensor module may include a module microcomputer providedseparately from the controller. The module microcomputer may determinewhether the knock input received from the microphone is a predeterminedknock input, and may transmit the result of the determination to thecontroller. That is, the module microcomputer may determine whether apredetermined knock input has been performed (i.e. whether normal userinput for operating the illumination device has been performed), and thecontroller, which directly controls the illumination device, may notperform such determination.

A support member for receiving the microphone module and for tightlyattaching the microphone module to the front panel may be included.Here, the front panel may be a panel provided at the front of the door,which defines a see-through region. The front panel may have a region inwhich a user knock input is performed. Consequently, the front panel maybe a medium through which knock vibration input by the user istransmitted to the microphone module. That is, the front panel may be amedium through which a sound wave generated by the knock vibration istransmitted to the microphone module. Consequently, the front panel maybe formed such that the uniformity and continuity of the medium aremaintained.

The support member may include a holder for receiving the microphonemodule and supporting the microphone module so as to be tightly attachedto the front panel. The holder may be elastically supported so as to betightly attached to the front panel. In particular, the holder may bemade of an elastic material. When the holder is compressed, therefore,the holder may have elastic restoring force. As a result, the holder maycontinuously push the microphone module so as to be tightly attached tothe front panel.

In accordance with another aspect of the present invention, there isprovided a refrigerator including a cabinet having a storage compartmenttherein, a main door hinged to the cabinet for opening and closing thestorage compartment, the main door having an opening formed therein, asub storage compartment provided in the rear of the main door, anillumination device for illuminating the sub storage compartment, a subdoor hinged to the main door or the cabinet for opening and dosing thesub storage compartment, the sub door having an opening formed therein,a panel assembly provided at the sub door, the panel assembly having afront panel provided at the front of the sub door, a microphone modulefor sensing a knock input applied to the sub door as a sound wave, and acontroller for operating the illumination device such that light istransmitted through the panel assembly when the knock input is sensed,whereby the sub storage compartment can be seen through the opening inthe sub door from outside the sub door.

The illumination device may be provided so as to illuminate a mainstorage compartment in addition to the sub storage compartment.

In accordance with another aspect of the present invention, there isprovided a refrigerator including a cabinet having a storage compartmenttherein, an illumination device for illuminating the interior of thestorage compartment, a door hinged to the cabinet for opening andclosing the storage compartment, the door having an opening formedtherein and a panel assembly having a front panel provided at the frontthereof, a knock sensor module including a microphone module for sensinga sound wave generated by a knock input applied to the door and a modulemicrocomputer for determining whether the knock input is a predeterminedknock based on the sensed sound wave, and a controller providedseparately from the module microcomputer for receiving a knock-on signalfrom the module microcomputer and operating the illumination device suchthat light is transmitted through the panel assembly, whereby theinterior of the storage compartment can be seen from outside the door.

The door may be a main door for opening and closing the storagecompartment or a sub door for opening and closing a sub storagecompartment provided in the main door. The sub door may be located infront of the main door. That is, the sub door and the main door may beprovided in the forward-rearward direction so as to overlap each other.The sub door may be inserted into the main door. That is, the sub doormay be inserted into the inside of the main door in the radialdirection.

The microphone module may include a microphone and a microphonereceiving part for receiving the microphone, the microphone receivingpart being provided to tightly attach the microphone to the front panel,which is the medium through which vibrations are transmitted.

The knock sensor module may include a noise filter for removing noisefrom the signal received from the microphone and an amplifier foramplifying the signal from which the noise has been removed. The modulemicrocomputer may determine whether the knock input is a predeterminedknock based on the signal amplified by the amplifier.

The knock sensor module may include a printed circuit board (PCB) onwhich the module microcomputer is mounted and a signal line forconnecting the controller to the PCB.

The length of the signal line may be less than about 10 cm.Consequently, it is possible to reduce the effects of noise, which iscaused by an external electromagnetic field and is then introduced intothe signal line.

The knock sensor module may include a noise sensor provided separatelyfrom the microphone for sensing external noise in order to preventincorrect sensing due to external noise or abnormal vibration.

The knock sensor module may include a subtractor for subtracting asignal received from the noise sensor from the signal received from themicrophone to remove the effects caused by the signal received from thenoise sensor.

The module microcomputer may determine whether the knock input is apredetermined knock after receiving the signal from the microphone andthe signal from the noise sensor.

Consequently, the effects of external noise in the microphone forsensing the knock input may be removed by the noise sensor. That is, themicrophone may sense both the knock input and external noise, or maysense only external noise. The effects of external noise may be removedby the noise sensor. Consequently, it is possible to greatly reduceincorrect recognition and malfunction due to external noise.

The noise sensor may include a second microphone and a second microphonereceiving part for receiving the second microphone, the secondmicrophone receiving part being provided to space the second microphoneapart from the front panel, which is the medium through which vibrationsare transmitted.

The refrigerator may further include a human body sensor for sensing auser approach to the refrigerator.

The controller may perform control such that the illumination device isnot operated despite the knock-on signal in the case in which the humanbody sensor does not sense the user approach.

Of course, in the case in which the human body sensor does not sense theuser approach, the knock-on signal may not be generated. That is, themodule microcomputer may not generate a normal knock-on signal.

The human body sensor may be any one selected from among an ultrasonicsensor, a passive infrared (PIR) sensor, an IR sensor, and an imagesensor, which sense variation in the motion of a human body.

The microphone module may be mounted so as to be tightly attached to thefront or the rear of the front panel from the outside of the opening inthe radial direction.

In accordance with another aspect of the present invention, there isprovided a refrigerator including a cabinet having a storage compartmenttherein, an illumination device for illuminating the interior of thestorage compartment, a door hinged to the cabinet for opening andclosing the storage compartment, the door having an opening formedtherein and a panel assembly having a front panel provided at the frontthereof, a knock sensor module including a microphone module for sensinga sound wave generated by knock vibration applied to the front panel, acontroller for, upon determining that the knock vibration is apredetermined knock, operating the illumination device such that lightis transmitted through the panel assembly, whereby the interior of thestorage compartment can be seen from outside the door, and a correctionsensor provided separately from the microphone in order to preventincorrect sensing of the knock sensor module due to external noise orabnormal vibration.

The door may be a main door for opening and closing the storagecompartment or a sub door for opening and closing a sub storagecompartment provided in the main door. The sub door may be located infront of the main door. That is, the sub door and the main door may beprovided in the forward-rearward direction so as to overlap each other.The sub door may be inserted into the main door. That is, the sub doormay be inserted into the inside of the main door in the radialdirection.

The correction sensor may include a noise sensor having a secondmicrophone, the noise sensor being provided to sense external noise andto remove the sensed noise.

The knock sensor module may include a module microcomputer fordetermining whether the knock vibration is a predetermined knock basedon a signal received from the microphone and a signal received from thenoise sensor.

Upon determining that the knock vibration is a predetermined knock, themodule microcomputer may transmit a knock-on signal to the controller.

The knock sensor module may include a subtractor for subtracting thesignal received from the noise sensor from the signal received from themicrophone to remove the effects caused by the signal received from thenoise sensor.

The correction sensor may further include a human body sensor forsensing a user approach to the refrigerator.

The controller may perform control such that the illumination device isnot operated despite a determination that the knock vibration is apredetermined knock in the case in which the human body sensor does notsense the user approach. That is, when there is no user approach, apredetermined knock may be determined to be external disturbance, suchas external noise.

The knock sensor module may include a module microcomputer fordetermining whether the knock vibration is a predetermined knock basedon the signal received from the microphone. Upon determining that theknock vibration is the predetermined knock, the module microcomputer maytransmit a knock-on signal to the controller.

The controller may perform control such that the illumination device isoperated upon receiving both the knock-on signal from the modulemicrocomputer and a human body approach signal from the human bodysensor.

The module microcomputer may perform a determination as to both thehuman body approach received from the human body sensor and the knockinput received from the microphone. Consequently, the modulemicrocomputer may be a knock-on signal in the case in which both thehuman body sensing condition and the knock input condition aresatisfied. In this case, the controller may perform control such thatthe illumination device is operated upon receiving the knock-on signal.

The refrigerator may further include an elastic microphone receivingpart for receiving the microphone, the microphone receiving part beingtightly attached to the front panel to form a sealed space between themicrophone and the front panel.

In accordance with a further aspect of the present invention, there isprovided a refrigerator including a cabinet having a storage compartmenttherein, an illumination device for illuminating the interior of thestorage compartment, a door hinged to the cabinet for opening andclosing the storage compartment, the door having an opening formedtherein and a panel assembly having a front panel provided at the frontthereof, a vibration sensor for sensing knock vibration applied to thefront panel, a controller for, upon determining that the knock vibrationsensed by the vibration sensor is a predetermined knock, operating theillumination device such that light is transmitted through the panelassembly, whereby the interior of the storage compartment can be seenfrom outside the door, and a correction sensor provided separately fromthe vibration sensor in order to prevent incorrect sensing of thevibration sensor module due to external noise or abnormal vibration.

The vibration sensor may include any one selected from between amicrophone and an acceleration sensor.

The microphone may be provided to sense a sound wave transmitted throughthe front panel. Consequently, the sound wave may be a wave motiontransmitted through the interior of the front panel.

The acceleration sensor may be provided to sense vibrations transmittedthrough the front panel. That is, the acceleration sensor may beprovided to sense the vibration of the front panel. Consequently, theacceleration sensor may be a sensor for sensing a wave motiontransmitted through the surface of the front panel.

Upon determining that the knock vibration is a normal knock input basedon signals received from the vibration sensor and the correction sensor,the controller may operate the illumination device. The knock vibrationmay be determined to be a normal knock input based on the knock input tothe vibration sensor. That is, the knock vibration may be determined tobe a normal knock that is input based on the input sound wave orvibration. The correction sensor may be provided to sense the sound waveor vibration directly input by the user, rather than externaldisturbance. That is, the correction sensor may be a human body sensorfor sensing the user. That is, in the case in which it is determinedthat the knock vibration is a normal knock input based on the signalsensed by the vibration sensor and the human body is sensed by the humanbody sensor, i.e. in the case in which both conditions are satisfied, itmay be determined that the knock vibration is substantially a normalknock input. When both conditions are satisfied, the controller mayperform control such that the illumination device is operated.

In the case in which the knock vibration is determined to be a normalknock input after the effects of the external noise or abnormal externalvibration are removed through the vibration sensor and the correctionsensor, the controller may operate the illumination device.

Here, the vibration sensor and the correction sensor may be the samekind of sensors. In the case in which the vibration sensor substantiallyincludes a microphone for sensing a sound wave, the correction sensormay also include a microphone. In the case in which the vibration sensoris an acceleration sensor, the correction sensor may also be anacceleration sensor.

Consequently, the effects caused by the sound wave or vibration sensedby the correction sensor may be subtracted from the sound wave orvibration sensed by the vibration sensor.

First, in the case in which the vibration sensor and the correctionsensor include microphones, both the microphones sense external noise.When a normal knock input is performed in the state in which externalnoise is generated, the microphone of the vibration sensor may sense theexternal noise as well as the normal knock input. At this time, theeffects of the external noise sensed by the vibration sensor are removedin order to correctly determine the normal knock input. Of course, themicrophones may be mounted at different positions. That is, one of themicrophones may be mounted to effectively sense the normal knock input,and the other microphone may be mounted to effectively sense theexternal noise. Consequently, the microphone of the vibration sensor maybe provided in the state of being tightly attached to the front panel,and the microphone of the correction sensor may be provided such that itis not tightly attached to the front panel.

Next, in the case in which acceleration sensors are used as thevibration sensor and the correction sensor, the acceleration sensors maybe mounted at different positions. In addition, the acceleration sensorsmay be mounted on different media. The acceleration sensor used as thevibration sensor may be provided so as to be tightly attached to thefront panel, and the acceleration sensor used as the correction sensormay be provided so as to be tightly attached to a medium other than thefront panel. For example, the acceleration sensor used as the correctionsensor may be provided so as to be tightly attached to the cabinet, acap decoration part, or a hinge cover.

For example, when the refrigerator is vibrated due to strong externalvibration, the vibration sensor and the correction sensor sense similarvibrations. Consequently, the sensed vibrations may be offset toeffectively determine that such an input is not a knock input. Inparticular, when a normal knock input is performed in the state in whichan external vibration is generated, the acceleration sensor used as thevibration sensor may sense the external noise as well as the vibrationcaused by the knock input. However, the acceleration sensor used as thecorrection sensor may sense only the external noise. The reason for thisis that the two acceleration sensors are mounted on different media.Consequently, the effects of the external noise may be eliminated,thereby effectively determining a normal knock input.

Consequently, the correction sensor may be a kind of human body sensordifferent from the vibration sensor. Alternatively, the correctionsensor may be the same kind of sound wave sensor or acceleration sensoras the vibration sensor.

According to an embodiment of the present invention, it is possible toprovide a refrigerator configured such that at least a portion of a doorfor opening and closing a storage compartment is transparent such thatthe interior of the storage compartment can be seen without opening thedoor.

According to an embodiment of the present invention, it is possible toprovide a refrigerator including a see-through door, through which lightis transmitted, i.e. a refrigerator configured such that the interior ofthe storage compartment can be seen through the door from outside thedoor.

According to an embodiment of the present invention, it is possible toprovide a refrigerator having a selectively variable see-through door,i.e. a refrigerator configured such that a storage compartment cannotusually be seen through a door but such that the storage compartment canbe seen through the door as needed.

According to an embodiment of the present invention, it is possible toprovide a refrigerator configured such that user input for changing to asee-through door is easily performed and such that the externalappearance of the refrigerator, particularly the external appearance ofthe front of the door, is not deteriorated by the user input structure.

According to an embodiment of the present invention, it is possible toprovide a refrigerator configured such that the incidence of error inuser input for changing to a see-through door, recognition error, ormalfunctions can be reduced. In addition, it is possible to provide arefrigerator configured such that the user input recognition rate isincreased.

According to an embodiment of the present invention, it is possible toprovide a refrigerator configured such that a user's tap on a door iseffectively sensed for changing to a see-through door, thereby improvingconvenience in use.

According to an embodiment of the present invention, it is possible toprovide a refrigerator configured such that a user's tap on a door iseffectively sensed even though the position of the door on which theuser taps and the position at which the user's tap is sensed are spacedapart from each other.

According to an embodiment of the present invention, it is possible toprovide a refrigerator configured such that the position of a door onwhich a user taps is substantially extended to the entirety of the frontof the door using a sound wave transmitted through a medium.

According to an embodiment of the present invention, it is possible toprovide a refrigerator configured such that a knock input is effectivelysensed while the structure of the refrigerator is simplified to theexclusion of an expensive device, such as a touch panel.

According to an embodiment of the present invention, it is possible toprovide a refrigerator configured such that heat insulation performanceis secured and a door is stable and easy to manufacture.

According to an embodiment of the present invention, it is possible toprovide a refrigerator including a door having a black panel, such as aTV or a computer monitor, wherein the door is changed to a see-throughdoor based on illumination as needed, thereby reducing energyconsumption for changing to the see-through door.

According to an embodiment of the present invention, it is possible toprovide a refrigerator configured such that the entirety of asee-through region of a door is set to a knock input region, amicrophone module being mounted outside the see-through region toprevent the see-through region and the microphone module fromoverlapping each other, thereby providing an aesthetically pleasingappearance.

According to an embodiment of the present invention, it is possible toprovide a refrigerator including a knock sensor module constituted by amicrophone module and a module microcomputer to effectively remove noisegenerated in a signal line between a controller for controlling anillumination device and the knock sensor module.

According to an embodiment of the present invention, it is possible toprovide a refrigerator that is capable of effectively preventingexternal noise, external impact, and vibration of the refrigerator frombeing incorrectly recognized as a knock input. In particular, anembodiment of the present invention provides a refrigerator including acorrection sensor that is separate from a vibration sensor or a knocksensor module in order to effectively prevent negative effects caused byexternal disturbance.

According to an embodiment of the present invention, it is possible toprovide a refrigerator including a microphone module as an example of acorrection sensor to effectively prevent effects caused by externaldisturbance.

According to an embodiment of the present invention, it is possible toprovide a refrigerator including a human body sensor as an example of acorrection sensor for effectively solving problems caused when a knocksensor module recognizes an external disturbance as a knock input.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the spirit or scope of the invention. Thus, it isintended that the present invention cover the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents. The features of the aboveembodiments may be applied in combination with those of otherembodiments unless the features are contradictory or exclusive.

It will be understood that when an element or layer is referred to asbeing “on” another element or layer, the element or layer can bedirectly on another element or layer or intervening elements or layers.In contrast, when an element is referred to as being “directly on”another element or layer, there are no intervening elements or layerspresent. As used herein, the term “and/or” includes any and allcombinations of one or more of the associated listed items.

It will be understood that, although the terms first, second, third,etc., may be used herein to describe various elements, components,regions, layers and/or sections, these elements, components, regions,layers and/or sections should not be limited by these terms. These termsare only used to distinguish one element, component, region, layer orsection from another region, layer or section. Thus, a first element,component, region, layer or section could be termed a second element,component, region, layer or section without departing from the teachingsof the present invention.

Spatially relative terms, such as “lower”, “upper” and the like, may beused herein for ease of description to describe the relationship of oneelement or feature to another element(s) or feature(s) as illustrated inthe figures. It will be understood that the spatially relative terms areintended to encompass different orientations of the device in use oroperation, in addition to the orientation depicted in the figures. Forexample, if the device in the figures is turned over, elements describedas “lower” relative to other elements or features would then be oriented“upper” relative to the other elements or features. Thus, the exemplaryterm “lower” can encompass both an orientation of above and below. Thedevice may be otherwise oriented (rotated 90 degrees or at otherorientations) and the spatially relative descriptors used hereininterpreted accordingly.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention. Asused herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” when used in this specification, specify thepresence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof.

Embodiments of the disclosure are described herein with reference tocross-section illustrations that are schematic illustrations ofidealized embodiments (and intermediate structures) of the disclosure.As such, variations from the shapes of the illustrations as a result,for example, of manufacturing techniques and/or tolerances, are to beexpected. Thus, embodiments of the disclosure should not be construed aslimited to the particular shapes of regions illustrated herein but areto include deviations in shapes that result, for example, frommanufacturing.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this invention belongs. It will befurther understood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art andwill not be interpreted in an idealized or overly formal sense unlessexpressly so defined herein.

Any reference in this specification to “one embodiment,” “anembodiment,” “example embodiment,” etc., means that a particularfeature, structure, or characteristic described in connection with theembodiment is included in at least one embodiment. The appearances ofsuch phrases in various places in the specification are not necessarilyall referring to the same embodiment. Further, when a particularfeature, structure, or characteristic is described in connection withany embodiment, it is submitted that it is within the purview of oneskilled in the art to effect such feature, structure, or characteristicin connection with other ones of the embodiments.

Although embodiments have been described with reference to a number ofillustrative embodiments thereof, it should be understood that numerousother modifications and embodiments can be devised by those skilled inthe art that will fall within the spirit and scope of the principles ofthis disclosure. More particularly, various variations and modificationsare possible in the component parts and/or arrangements of the subjectcombination arrangement within the scope of the disclosure, the drawingsand the appended claims. In addition to variations and modifications inthe component parts and/or arrangements, alternative uses will also beapparent to those skilled in the art.

What is claimed is:
 1. A refrigerator, comprising: a cabinet having astorage compartment therein; an illumination device for illuminating aninterior of the storage compartment; a main door hinged to the cabinetand configured to open and close the storage compartment; and a sub doormounted to the main door or the cabinet and configured to be rotatedabout a sub door hinge, the sub door including a recess in which the subdoor hinge is mounted, wherein the sub door includes: a door framehaving an opening; a panel assembly to cover the opening and including afront panel provided in front of the recess and a vacuum insulationspace provided at a rear side of the front panel; and a knock sensor tosense a sound wave generated by a knock input applied to the sub doorand in contact with a rear surface of the front panel.
 2. Therefrigerator of claim 1, wherein the panel assembly further includes afirst insulation panel provided at the rear side of the front panel anda second insulation panel provided at a rear side of the firstinsulation panel, and wherein the vacuum insulation space is definedbetween the first insulation panel and the second insulation panel. 3.The refrigerator of claim 2, wherein the panel assembly further includesa sealing member disposed between the first insulation panel and thesecond insulation panel, and wherein one or more spacers is disposed inthe vacuum insulation space between the first insulation panel and thesecond insulation panel.
 4. The refrigerator of claim 3, wherein thesealing member is provided at a perimeter of the panel assembly.
 5. Therefrigerator of claim 2, wherein a distance between the front panel andthe first insulation panel is greater than a distance between the firstinsulation panel and the second insulation panel.
 6. The refrigerator ofclaim 2, wherein the first insulation panel comprises a hole and a plugto close the hole.
 7. The refrigerator of claim 6, wherein the panelassembly further comprises a frit glass to cover the plug.
 8. Therefrigerator of claim 1, wherein the knock sensor includes a microphoneto sense a sound wave generated by the knock input applied to the subdoor, and a microphone receiver that receives the microphone, andwherein the microphone receiver is in contact with the rear surface ofthe front panel.
 9. The refrigerator of claim 8, wherein the microphoneis spaced apart from the rear surface of the front panel such that aspace is defined between the microphone and the rear surface of thefront panel.
 10. The refrigerator of claim 1, wherein the front panelcomprises a viewing area and a non-viewing area, and wherein the knocksensor is mounted at the non-viewing area of the front panel.
 11. Therefrigerator of claim 1, wherein the door frame further includes areceiver to receive the knock sensor, and wherein the knock sensor is incontact with the rear surface of the front panel in a state in which theknock sensor is received in a location portion.
 12. The refrigerator ofclaim 11, wherein the door frame includes: an external door that definesa front side of the sub door, a door liner that defines a rear side ofthe sub door, cap decorations coupled to upper and lower ends of theexternal door and the door liner, and wherein the receiver is providedin one of the cap decorations.
 13. The refrigerator of claim 12, whereinthe knock sensor includes a microphone to detect a sound wave generatedby the knock input, and wherein the one of the cap decorations isprovided with a through hole through which the microphone extends. 14.The refrigerator of claim 1, wherein based on detecting the knock input,the illumination device is turned on such that an interior of thestorage compartment is viewable through the front panel of the sub doorfrom outside, and wherein the illumination device is turned off afterbeing turned on for a predetermined period of time.
 15. A sub door for arefrigerator, the sub door being configured to be mounted to a main dooror a cabinet of the refrigerator and rotated about a sub door hinge, thesub door comprising: a door frame having an opening and a recess inwhich the sub door hinge is mounted; a front panel provided in front ofthe opening and the recess; a first insulation panel provided at a rearside of the front panel; a second insulation panel provided at a rearside of the first insulation panel, wherein a vacuum insulation space isdefined between the first insulation panel and the second insulationpanel; and a knock sensor configured to sense a knock applied to the subdoor, wherein the knock sensor faces a rear surface of the front panel.16. The sub door of claim 15, further comprising a sealing memberdisposed between and at a perimeter of the first insulation panel andthe second insulation panel, wherein one or more spacers is disposed inthe vacuum insulation space between the first insulation panel and thesecond insulation panel.
 17. The sub door of claim 15, wherein the knocksensor includes a microphone to sense a sound wave generated by theknock applied to the sub door.
 18. A refrigerator comprising the subdoor of claim
 15. 19. A refrigerator, comprising: a cabinet having astorage compartment therein; an illumination device for illuminating aninterior of the storage compartment; a main door hinged to the cabinetand configured to open and close the storage compartment; and a sub doormounted to the main door or the cabinet and configured to be rotatedabout a sub door hinge, the sub door including a recess in which the subdoor hinge is mounted, wherein the sub door includes: a door framehaving an opening; a panel assembly to cover the opening and including afront panel provided in front of the recess; and a knock sensor to sensea sound wave generated by a knock input applied to the sub door and incontact with a rear surface of the front panel, wherein the door framefurther includes a receiver to receive the knock sensor, and wherein theknock sensor is in contact with the rear surface of the front panel in astate in which the knock sensor is received in a location portion.